Voyager 1

 

Big Bang Nucleosynthesis and Neutrino Physics

A clever new paper uses the observational evidence from astronomy supporting Big Bang Nucleosynthesis to constrain the hypotheses of sterile neutrinos or non-standard neutrino interactions to almost the level reached from Earth bound experiments and other cosmology observations. 

Their findings tend to reinforce the Standard Model view that there are only three flavors of neutrinos and that they have only the interactions allowed by the Standard Model (i.e. weak force interactions and neutrino oscillations according to the PMNS matrix).

In this work we investigate the impact of two phenomenological Beyond the Standard Model (BSM) scenarios concerning the role of neutrinos in the early universe: non-standard neutrino interactions (NSI) and non-unitary three-neutrino mixing. 

We evaluate the impact of these frameworks on two key cosmological observables: the effective number of relativistic neutrino species (Neff), related to neutrino decoupling, and the abundances of light elements produced at Big Bang Nucleosynthesis (BBN). For the first time, neutrino CC-NSI with quarks and non-unitary three-neutrino mixing are studied in the context of BBN, and the constraints on such interactions are found to be remarkably competitive with terrestrial experiments. In the case of non-unitarity, the combination between neutrino decoupling and BBN imposes stringent constraints that can either mildly favour the existence of New Physics (NP), or reinforce the SM, depending on the choice of the experimental nuclear rates involved in the BBN calculation.

Gabriela Barenboim, Stefano Gariazzo, Alberto Sánchez-Vargas, "Big Bang Nucleosynthesis as a probe of non-standard neutrino interactions and non-unitary three-neutrino mixing" arXiv:2503.21998 (March 27, 2025).

Did Homo Sapiens Arise As A Hybrid?

In addition to being highly model dependent and unsupported by ancient DNA data, and hence somewhat speculative, this is really a less revolutionary proposal than it seems. 

Modern humans still arise in Africa (including a hypothetical admixture event that gives rise to the new species ca. 290,000 years ago). Basically, it is just proposing that in addition to the Neanderthal admixture shared by all non-Africans, and the Denisovan admixture that took place in the first generation of modern humans to reach Asia, there was an 20% admixture event from Homo erectus involving all modern humans associated with the emergence of the new species.

In their model, the 80% source, probably Homo heidelbergensis is also ancestral to Neanderthals and Denisovans, evolves from from Homo erectus about 1,500,000 years ago and suffers a severe bottleneck period, while the 20% Homo erectus ancestry was exclusive to Homo sapiens and was probably initially a larger percentage as a result of an admixture event in Africa about 290,000 years ago. The Homo erectus ancestry percentage was reduced in percentage over time due to its inferior selective fitness in most parts of the Homo erectus genome that have an impact on phenotypes (i.e. that have any actual discernible effect).

The evolutionary path leading to the rise of modern humans is full of twists and turns, and the latest surprise reveals that our species likely sprung forth from two ancient intermingling populations. A new study has confirmed that these groups first diverged from each other around 1.5 million years ago and later merged back together 300,000 years ago, initiating a genetic mixing event that culminated with the birth of modern humans.

The study, published in Nature Genetics, completely rewrites the story of humans. Scientists have long believed that Homo sapiens first appeared in Africa somewhere between 200,000 years and 300,000 years ago, having descended from a single ancestral lineage. The idea of genetic admixture flips the script, however, showing that human origins are much more complex than previously thought.

The researchers . . . tapped into modern human DNA from the 1000 Genomes Project, an international catalog filled with human genomes from a variety of populations. The research team created a computational algorithm called cobraa, which was designed to represent the event of an ancestral population splitting and rejoining. . . . 

With this method, they were able to produce a structured model that displayed two ancestral populations breaking apart in ancient times. In the years after this divergence, one of the populations experienced major fluctuations in size.

“Immediately after the two ancestral populations split, we see a severe bottleneck in one of them — suggesting it shrank to a very small size before slowly growing over a period of one million years,” said co-author Aylwyn Scally from the University of Cambridge’s Department of Genetics, in a statement. “This population would later contribute about 80 percent of the genetic material of modern humans and also seems to have been the ancestral population from which Neanderthals and Denisovans diverged.”

The second population, meanwhile, contributed 20 percent to the genetic makeup of modern humans. The researchers found that many of the genes this group passed along to humans were not located near regions of the genome corresponding to gene functions; this could reflect a concept called purifying selection, which is the process of natural selection filtering out harmful mutations. However, the researchers believe that some of the genes from the second population may have still been integral to brain development in modern humans.  . . .

An element of mystery still surrounds the identity of these ancestral populations. The researchers point to Homo erectus and Homo heidelbergensis as potential answers since they were present in Africa around the time of the genetic admixture, but further research is needed to match genetic ancestors with fossil groups.

Nature Genetics. A structured coalescent model reveals deep ancestral structure shared by all modern humans

From Discover Magazine. The abstract of the open access paper states:

Understanding the history of admixture events and population size changes leading to modern humans is central to human evolutionary genetics. Here we introduce a coalescence-based hidden Markov model, cobraa, that explicitly represents an ancestral population split and rejoin, and demonstrate its application on simulated and real data across multiple species. 

Using cobraa, we present evidence for an extended period of structure in the history of all modern humans, in which two ancestral populations that diverged ~1.5 million years ago came together in an admixture event ~300 thousand years ago, in a ratio of ~80:20%. Immediately after their divergence, we detect a strong bottleneck in the major ancestral population. 

We inferred regions of the present-day genome derived from each ancestral population, finding that material from the minority correlates strongly with distance to coding sequence, suggesting it was deleterious against the majority background. Moreover, we found a strong correlation between regions of majority ancestry and human–Neanderthal or human–Denisovan divergence, suggesting the majority population was also ancestral to those archaic humans.

A Grab Bag Of Astrophysics and High Energy Physics Papers

Astrophysics Papers

Black hole physicists are skeptical of leading cosmology paradigms.

The cosmological constant, cosmological inflation, and string theory, all lack majority support among black hole physicists. Also, a majority of them take the position that the Big Bang means that "the universe evolved from a hot dense state", not "an absolute beginning time" which is the weaker of the two possible definitions of what the Big Bang theory means.

The purpose of this survey is to take a snapshot of the attitudes of physicists, which may be useful to sociologists and historians of science. A total of 85 completed surveys were returned out of 151 registered participants of the "Black holes Inside and out" conference, held in Copenhagen in 2024. The survey asked questions about the nature of black holes and some of the most contentious issues in fundamental physics. A number of surprising results were found. 

For example, some of the leading frameworks, such the cosmological constant, cosmic inflation, or string theory, while most popular, gain less than majority of votes from the participants. The only statement that gains majority approval (by 68% of participants) was that the Big Bang means that "the universe evolved from a hot dense state", not "an absolute beginning time". 

This provides reasons for caution in describing ideas as consensus in the scientific community when a more nuanced view may be justified.

From here.

MOND still works.

Meanwhile, MOND still works to explain early galaxies, while LamdaCDM theory does not:

We investigate the shape and morphology of early-type galaxies (ETGs) within the framework of Modified Newtonian Dynamics (MOND). 

Building on our previous studies, which demonstrated that the monolithic collapse of primordial gas clouds in MOND produces galaxies (noted throughout as 'model relics' in the context of this work) with short star formation timescales and a downsizing effect as observationally found, we present new analyses on the resulting structural and morphological properties of these systems. Initially, the monolithically formed galaxies display disk-like structures. 

In this study, we further analyze the transformations that occur when these galaxies merge, observing that the resulting systems (noted throughout as 'merged galaxies' in the context of this work) take on elliptical-like shapes, with the (V_rot/V_sigma) - ellipticity relations closely matching observational data across various projections. We extend this analysis by examining the isophotal shapes and rotational parameter (lambda_R) of both individual relics and merged galaxies. 

The results indicate that ETGs may originate in pairs in dense environments, with mergers subsequently producing elliptical structures that align well with observed kinematic and morphological characteristics. Finally, we compare both the model relics and merged galaxies with the fundamental plane and Kormendy relation of observed ETGs, finding close agreement. Together, these findings suggest that MOND provides a viable physical framework for the rapid formation and morphological evolution of ETGs.

Robin Eappen, Pavel Kroupa, "Scaling relations of early-type galaxies in MOND" arXiv:2503.15600 (March 19, 2025) (published in Galaxies 2025, 13, 22).

Primordial black hole dark matter still doesn't work.

New strict bounds on primordial black holes as dark matter that don't share systemic errors with other comparably strictly bounding observations have been found. This is consistent with a mountain of evidence strongly disfavoring primordial black holes as a significant source of dark matter phenomena.

High Energy Physics Papers

Heavy neutrinos have not been found.

There is no evidence from the LHC for a "heavy neutral lepton" (basically a heavy neutrino) up to masses of 14.5 GeV. This is not all that huge of a finding as W and Z boson decays largely rule out neutrinos beyond the three Standard Model active neutrinos with masses of less than about 45 GeV.

Hints of up to two kinds of possible heavy Higgs bosons.

Finally, there are resonances that could be arguably interpreted at a 152 GeV Higgs boson S, and another heavy Higgs boson H that decays to two S bosons at the LHC. 

Note the while the observational evidence of the neutral scalar S boson resonance, conceptualized as an intermediate mass Higgs boson (relative to the Standard Model Higgs boson which is an electromagnetically neutral, spin-0, even parity, 125 GeV particle with couplings proportional to the Standard Model fundamental particle masses) is very strong, the evidence of a heavy neutral H boson resonance that is a heavy Higgs boson isn't a part of the simplified model examined that is as definitively established. It would have to have a mass of at least about 302 GeV, but even its mass does not seem to have been definitively pinned down. 

Despite the high statistical significance of the resonance, I wouldn't consider it established yet for reasons including a lack of replication so far, and a lack of a full exploration of the implications of the hypothesized two new fundamental bosons. I personally also need to take some time to figure out what couplings and other properties it is proposed to have, and more generally, to better understand the theory behind it. This latest paper is also not peer reviewed or published yet, although there is no good reason to think that this won't happen.

Aside from popping into existence in high energy physics experiments and decaying, ultimately, into W bosons and b quarks and an invisible decay mode, it isn't clear what phenomenological impact these heavy Higgs bosons would have, or what the apparent invisible decay mode of the S boson would be (the default assumption, without more Standard Model physics, would be neutrinos). 

It also isn't clear to me at this time if alternative explanations for this resonance that do not involve new physics have been considered or proposed. But both the H boson and the S boson seem to be much more massive than any hadron with two to six valence quarks. The S boson, at least, is also too light and apparently too long lived, to have a top quark component. Could the H and S bosons be simply excited resonances of the 125 GeV Standard Model Higgs boson? I've seen proposals along those lines before in the literature (prior to the discovery of these resonances).

But, these proposed new particles are more credible than, for example, the X17 boson hypothesis.

The Higgs boson discovery at the Large Hadron Collider (LHC) at CERN confirmed the existence of the last missing particle of the Standard Model (SM). The existence of new fundamental constituents of matter beyond the SM is of great importance for our understanding of Nature. 

In this context, indirect (non-resonant) indications for new scalar bosons were found in the data from the first run of the LHC, taken between 2010 and 2012 at CERN: an excess in the invariant mass of muon-electron pairs, consistent with a new Higgs boson (S) with a mass of 150±5 GeV. Other processes with multiple leptons in the final state, moderate missing energy, and possibly (bottom quark) jets exhibit deviations from the SM predictions. These anomalies can be explained within a simplified model in which a new heavy Higgs boson H decays into two lighter Higgses S. This lighter Higgs S subsequently decays to W bosons, bottom quarks and has also an invisible decay mode.

Here, we demonstrate that using this model we can identify narrow excesses in di-photon and Z-photon spectra around 152 GeV. By incorporating the latest measurements of di-photons in association with leptons, we obtain a combined global significance of 5.4σ. 

This represents the highest significance ever reported for an excess consistent with a narrow resonance beyond the SM (BSM) in high-energy proton-proton collision data at the LHC. Such findings have the potential to usher in a new era in particle physics - the BSM epoch - offering crucial insights into unresolved puzzles of nature.

Srimoy Bhattacharya, et al., "Emerging Excess Consistent with a Narrow Resonance at 152 GeV in High-Energy Proton-Proton Collisions" arXiv:2503.16245 (March 20, 2025).

Incidentally, the paper also cites the two main papers that predicted the existence of the Standard Model Higgs boson, which I reproduce below for future reference:

* Higgs, P.W.: Broken symmetries, massless particles and gauge fields. Phys. Lett. 12, 132–133 (1964) https://doi.org/10.1016/0031-9163(64)91136-9

* Englert, F., Brout, R.: Broken Symmetry and the Mass of Gauge Vector Mesons. Phys. Rev. Lett. 13, 321–323 (1964) https://doi.org/10.1103/PhysRevLett.13. 321

Problems For Self-Interacting Dark Matter

In MOND, due to the external field effect, you expect a bimodal distribution. In CDM is should be a more continuous distribution. SIDM should have a single value.

Self-interacting dark matter (SIDM) has been proposed to address small-scale challenges faced by the cold dark matter (CDM) paradigm, such as the diverse density profiles observed in dwarf galaxies. In this study, we analyze the kinematics of dwarf galaxies by incorporating the effects of gravothermal core collapse into SIDM models using a semi-analytical subhalo framework. Our analysis covers the stellar kinematics of both classical and ultrafaint dwarf galaxies. The results indicate a bimodal preference for small and large self-interaction cross sections in ultrafaint dwarf galaxies, while in classical dwarfs, larger cross sections progressively decrease the model's statistical support. The combined analysis decisively prefers CDM to SIDM when the self-interaction cross section per unit mass, σ/m, exceeds ∼0.2 cm2/g, if a velocity-independent cross section is assumed. Our study significantly enhances our understanding of dark matter dynamics on small scales.

Shin'ichiro Ando, et al., "Stringent Constraints on Self-Interacting Dark Matter Using Milky-Way Satellite Galaxies Kinematics" arXiv:2503.13650 (March 17, 2025).

Celtic Origins Traced With Ancient DNA

The Urnfield culture probably was a major factor spreading Celtic languages, and the Celtic languages and culture probably originated not with the Hallstatt Culture but with an early demic diffusion of an earlier culture found in Romania around 2,000 BCE to 1,200 BCE. The body text of the introduction explains that:

The debate is currently focused around three main models: (1) a Late Neolithic/Early Bronze Age spread along the Atlantic seaboard linked to the Bell Beaker Culture; (2) a Bronze Age spread from France, Iberia or Northern Italy; and (3) a Late Bronze Age/Early Iron Age spread from Central Europe associated with the Hallstatt and La Tène Cultures. Thus, the appearance and dispersal of the Celtic language constitutes a key question concerning the cultural formation of Bronze and Iron Age Europe.

In an accompanying paper, we report the generation of 752 new genomes, including 126 originating from France, Germany, Austria, and the British Isles, which are of immediate relevance to these questions.

Figure 2 in the paper looks at relative contributions of ancestry across Europe around 2300 BCE and 500 BCE.

Celtic languages, including Irish, Scottish Gaelic, Welsh and Breton, are today restricted to the Northern European Atlantic seaboard. However, between 3 and 2 thousand years before present (BP) Celtic was widely spoken across most of Europe. 

While often associated with Bell Beaker-related populations, the spread of this prominent Indo-European linguistic cluster remains debated. Previous genomic investigations have focused on its arrival to specific regions: Britain, Iberia and Southwestern Germany. 

Here, we utilize new genomic data from Bronze and Iron Age Europe to investigate the population history of historically Celtic-speaking regions, and test different linguistic theories on the origins and early spread of the Celtic languages. We identify a widespread demographic impact of the Central European Urnfield Culture. We find ancestry associated with its Knovíz subgroup in the Carpathian Basin to have formed between 4 – 3.2 kyr BP, and subsequently expanded across much of Western Europe between 3.2 and 2.8 kyr BP. This ancestry further persisted into the Hallstatt Culture of France, Germany and Austria, impacting Britain by 2.8 kyr BP and Iberia by 2.5 kyr BP. 

These findings support models of an Eastern Central rather than a Western European center of spread for a major component of all the attested Celtic languages. Our study demonstrates, yet again, the power of ancient population genomics in addressing long-standing debates in historical linguistics.

Hugh McColl, et al., "Tracing the Spread of Celtic Languages using Ancient Genomics" bioRxiv (March 1, 2025). More commentary and analysis at Bernard's blog.

Humans In African Jungles 150,000 Years Ago

Modern humans existed in wet tropical forests of West Africa about 150,000 years ago, contrary to the believe that humans could only survive in this kind of ecological environment through trade with farmers.

Humans emerged across Africa shortly before 300 thousand years ago (ka). Although this pan-African evolutionary process implicates diverse environments in the human story, the role of tropical forests remains poorly understood. 

Here we report a clear association between late Middle Pleistocene material culture and a wet tropical forest in southern Côte d’Ivoire, a region of present-day rainforest. Twinned optically stimulated luminescence and electron spin resonance dating methods constrain the onset of human occupations at Bété I to around 150 ka, linking them with Homo sapiens. Plant wax biomarker, stable isotope, phytolith and pollen analyses of associated sediments all point to a wet forest environment. 

The results represent the oldest yet known clear association between humans and this habitat type. The secure attribution of stone tool assemblages with the wet forest environment demonstrates that Africa’s forests were not a major ecological barrier for H. sapiens as early as around 150 ka.

Eslem Ben Arous, et al.,"Humans in Africa’s wet tropical forests 150 thousand years ago" Nature (February 26, 2025).

Galaxy Rotation Direction Is Not Random

I note this fact without exploring the most speculative explanations for this still unsolved problem in astrophysics and cosmology.

The $10 billion telescope, which began observing the cosmos in the Summer of 2022, has found that the vast majority of deep space and, thus the early galaxies it has so far observed, are rotating in the same direction. While around two-thirds of galaxies spin clockwise, the other third rotates counter-clockwise.

In a random universe, scientists would expect to find 50% of galaxies rotating one way, while the other 50% rotate the other way. This new research suggests there is a preferred direction for galactic rotation.

From here citing this paper whose abstract is also provided:

JWST provides a view of the Universe never seen before, and specifically fine details of galaxies in deep space. JWST Advanced Deep Extragalactic Survey (JADES) is a deep field survey, providing unprecedentedly detailed view of galaxies in the early Universe. The field is also in relatively close proximity to the Galactic pole. Analysis of spiral galaxies by their direction of rotation in JADES shows that the number of galaxies in that field that rotate in the opposite direction relative to the Milky Way galaxy is ∼50 per cent higher than the number of galaxies that rotate in the same direction relative to the Milky Way. The analysis is done using a computer-aided quantitative method, but the difference is so extreme that it can be noticed and inspected even by the unaided human eye. These observations are in excellent agreement with deep fields taken at around the same footprint by Hubble Space Telescope and JWST. 

The reason for the difference may be related to the structure of the early Universe, but it can also be related to the physics of galaxy rotation and the internal structure of galaxies. In that case the observation can provide possible explanations to other puzzling anomalies such as the H(o) tension and the observation of massive mature galaxies at very high redshifts.

Lior Shamir, "The distribution of galaxy rotation in JWST Advanced Deep Extragalactic Survey" 538(1) Monthly Notices of the Royal Astronomical Society 76–91 (February 17, 2025). https://doi.org/10.1093/mnras/staf292

Why Do We Kiss?

Why do we kiss? Is there an evolutionary advantage to it? This article tries to answer that question.

A kiss has been a signal of special affection across continents and cultures for millennia. Between times and peoples, social norms invariably prescribe kissing to specific affiliations and contexts, implying deeper biological bases. Why the protruding of the lips and slight suction when touching another? 

Capuchin monkeys stick their fingers in their friends' eyes as sign of affection, why have humans developed kissing? 

Here I briefly review proposed hypotheses for the evolution of human kissing. Great ape social behavior suggests that kissing is likely the conserved final mouth-contact stage of a grooming bout when the groomer sucks with protruded lips the fur or skin of the groomed to latch on debris or a parasite. The hygienic relevance of grooming decreased over human evolution due to fur-loss, but shorter sessions would have predictably retained a final “kissing” stage, ultimately, remaining the only vestige of a once ritualistic behavior for signaling and strengthening social and kinship ties in an ancestral ape.

Adriano R. Lameira, "The evolutionary origin of human kissing" Evolutionary Anthropology (October 17, 2024) https://doi.org/10.1002/evan.22050

More Researchers Look At Gravitational Self-Interaction

Another gravity based explanation of dark matter phenomena taking an approach somewhat similar to that of Deur who is cited at endnote 11. Milgrom (the author of MOND) is cited at endnotes 23, 24, and 25.

We derive the first analytical formula for the density of "Dark Matter" (DM) at all length scales, thus also for the rotation curves of stars in galaxies, for the baryonic Tully-Fisher relation and for planetary systems, from Einstein's equations (EE) and classical approximations, in agreement with observations. 

DM is defined in Part I as the energy of the coherent gravitational field of the universe, represented by the additional equivalent ordinary matter (OM), needed at all length scales, to explain classically, with inclusion of the OM, the observed coherent gravitational field. 

Our derivation uses both EE and the Newtonian approximation of EE in Part I, to describe semi-classically in Part II the advection of DM, created at the level of the universe, into galaxies and clusters thereof. This advection happens proportional with their own classically generated gravitational field g, due to self-interaction of the gravitational field. 

It is based on the universal formula rD=lgg'g' for the density rD of DM advected into medium and lower scale structures of the observable universe, where l is a universal constant fixed by the Tully-Fisher relations. Here g' is the gravitational field of the universe; g' is in main part its own source, as implied in Part I from EE. 

We start from a simple electromagnetic analogy that helps to make the paper generally accessible. This paper allows for the first time the exact calculation of DM in galactic halos and at all levels in the universe, based on EE and Newtonian approximations, in agreement with observations.

Peter H. Handel, Klara E. Splett, "Calculation of Dark Matter as a Feature of Space-Time" arXiv:2503.09804 (March 12, 2025) (published in Foundations of Physics (2023) 53:86) https://doi.org/10.1007/s10701-023-00705-x

Cave Paintings Track Mating And Birthing Cycles Of Prey

A study from 2023, that has come to my attention, convincingly argues that symbolic marking in cave painting of animals made by European hunter-gatherers track the number of lunar months after the start of their year, that the animals the markings are associated with have their mating season and birthing season. The paper is:

Bacon et al., "An Upper Palaeolithic Proto-writing System and Phenological Calendar" (2023) DOI: 10.1017/S0959774322000415

Related video here. 

Early Homo Erectus In Spain And Where It Fits In The Larger Narrative

Overview

Anthropologists have found partial Homo erectus remains in Spain from 1.1-1.4 million years ago, adding to 1.97 million year old Homo erectus remains in Grăunceanu, Romania, and 1.77-1.85 million year old Homo erectus remains in Dmanisi, Georgia. 

Homo erectus first appears in Africa. Outside of Africa, Homo erectus remains are most often found in Indonesia and China, dating from around 108,000 years ago in Southeast Asia, back to about 70,000 years after this species evolved in Africa. 

Homo erectus went extinct in most of the world around 1,000,000 years ago, but persisted longer in Southeast Asia and possibly in East Asia, and relict populations of Homo erectus probably admixed with Denisovans at some point when both species existed. A major population bottleneck described below, probably took place in Homo erectus starting around 930,000 years ago, but it didn't result in the complete extinction of the species. Homo erectus was probably extinct by the time that modern humans first ventured beyond South Asia (not long after the Toba eruption ca. 75,000 years ago). It is plausible that the Toba eruption, followed by first contact with modern humans, may have led to the final extinction of Homo erectus, to the final extinction of H. floresiensis and H. luzonensis, and also to the extinction of Denisovans over most of their range (with the last relict Denisovans in Tibet probably going extinct in connection with their contacts with modern humans in this remote place).

We know that Homo erectus evolved in Africa rather than Eurasia, because that is where the species that Homo erectus evolved from, mostly likely H. habilis, but possibly some other African archaic hominin, was located at the time, and not just because the oldest Homo erectus remains are found there.

The oldest identified H. erectus specimen is a 2.04 million year old skull, DNH 143, from Drimolen, South Africa, coexisting with the australopithecine Paranthropus robustus. H. erectus dispersed out of Africa soon after evolution, the earliest recorded instances being H. e. georgicus 1.85 to 1.78 million years ago in Georgia and the Indonesian Mojokerto and Sangiran sites 1.8 to 1.6 million years ago.

(The quoted Wikipedia summary hasn't been updated to reflect the Romanian discovery announced earlier this year.)

Half a million years and a few hundred meters away from this site, there are Homo antecessor remains, from a time when Homo erectus had gone extinct in Europe, almost 700,000 years before Homo erectus went extinct in Asia.

The New Discovery

ATE7-1 fossil face (right) with mirrored 3D model (left). Credit: Maria D. Guillén / IPHES-CERCA / Elena Santos / CENIEH

When the global timeline passed one million years ago, more than half the span of hominin presence in Eurasia had already passed by. The earliest archaeological evidence in Eurasia is more than two million years old—found in places like Shangchen, China, and the Dawqara Formation of Jordan. Just this year Grăunceanu, Romania, joined the list of early archaeological traces of hominins in Europe, dating to an estimated 1.97 million years ago.

Still, I think about the threshold of one million years ago quite often. The number of sites in Eurasia with hominin evidence before one million years ago has grown quite large. It would have been hard to imagine this in 1990, when many scientists wondered if any sites in Eurasia were really older than this. Today there are many. And yet, the number of sites with fossils of hominins is quite a lot smaller than the number with stone artifacts or cutmarked animal bones. Most are in China or Indonesia, in addition to the exceptional site of Dmanisi, Georgia.

In western Europe there may be only two such sites, both in Spain: Sima del Elefante and Barranco Léon.

This week Rosa Huguet and collaborators have reported on a significant new addition to this very humble record. In work at Sima del Elefante in 2022, excavators uncovered a fragmentary facial skeleton, designated as ATE7-1. The estimated age of this fossil face is between 1.4 million and 1.1 million years ago. The new fossil joins two other hominin fossils from this cave deposit, within the same range of ages, a finger bone and a fragment of the front portion of a mandible with several worn teeth, ATE9-1. These fossils have been previously published, the mandible in 2008.

None of these fossils provide much to go on. Huguet and coworkers compared the facial anatomy of ATE7-1 with fossil faces attributed to Homo erectus from Dmanisi, Georgia, and Sangiran, Indonesia. They also compared the face to fossils from Gran Dolina, Spain, attributed to Homo antecessor. This site is located only a few hundred meters from Sima del Elefante but represents hominins and stone artifacts from around 780,000 years ago—as much as a half million years or more later than Sima del Elefante.

The ATE7-1 face is more like most H. erectus faces than either is like the later Gran Dolina fossils.

From John Hawks.

Context

Where does this discovery fit in the larger narrative of archaic hominin evolution?

Neanderthals, Denisovans, and modern humans (i.e. Homo sapiens) all share a Homo erectus ancestor and probably also at least one intermediate archaic hominin ancestor that evolved from Homo erectus.

The oldest archaeological evidence of modern humans, which is, order of magnitude consistent with age estimates for the most recent common ancestor of all modern human uniparental Y-DNA and mtDNA lineages, is about 300,000 years ago in Africa. Modern humans first left Africa around 125,000 to 100,000 years ago, and did so via the Middle East rather than Iberia. But the lion's share of non-African modern humans appear to be descended from a later wave of modern human expansion out of Africa about 50,000-74,000 years ago, with the lion's share of that wave closer to 50,000 years ago than 74,000 years ago. Neanderthal populations largely stalled this expansion into Europe until about 40,000 years ago. One or more of the hominin populations of Southeast Asia, and the jungles of Southeast Asia, probably stalled modern human expansion via the Southern route into Asia until around the time of the Toba eruption around 74,000 years ago (with the eruption possibly weakening these barriers and possibly also creating a reason for the modern humans of South Asia to expand to the Southeast).

The oldest Neanderthal remains are about 430,000 years old. Neanderthals were moribund by 40,000 years ago (with modern human Cro-Magnon people entering Europe around the same time that Neanderthals became extinct and overlapping with them for periods of a thousand or two thousand years or so in any one place), with the final relict population going extinct around 29,000 years ago. The leading explanations for Neanderthal extinction include a wave of volcanic eruptions, climate change, and the growing superiority of modern human hunter-gatherers due to their cultural evolution (e.g. stone technologies and the domestication of dogs) and/or genetic evolution. The range of Neanderthals extended from Northern Wales to the Middle East to South Asia and the Altai Mountains. There was significant Neanderthal admixture with modern humans, probably around 50,000-100,000 years ago (the latest estimates tend to favor a more recent date) in the vicinity of the Middle East or Iran (leaving a DNA legacy in all non-African modern humans), and there was also a more modern admixture with Altai Neanderthals (leaving a DNA legacy in Asian modern humans). Non-Africans today have up to 2% Neanderthal DNA, with Asians having a little more than Europeans, although ancient DNA from modern humans in ancient Eurasia, much closer to Neanderthal admixture sometimes have higher percentages of Neanderthal admixture. Neanderthals had bigger brains than modern humans, but also a more static material culture and less diverse range of hunting prey heavily concentrated around large megafauna (suggesting reduced brain plasticity and less ability to adapt culturally rather than genetically), with modern humans also relied on a wider array of smaller prey like rabbits, smaller birds, fish, and other seafood. At the time of first contact with modern humans, the effective population size of Neanderthals was about ten times smaller than the effective population size of modern human Cro-Magnons, and the effective Neanderthal effective population size ranged from about 3,000-12,000 throughout their existence and was fractured into multiple more or less isolated regional subpopulations.

Wikipedia says this about the extinction of Neanderthals:

The extinction of Neanderthals was part of the broader Late Pleistocene megafaunal extinction event. Neanderthals were replaced by modern humans, indicated by the near-complete replacement of Middle Palaeolithic Mousterian stone technology with modern human Upper Palaeolithic Aurignacian stone technology across Europe (the Middle-to-Upper Palaeolithic Transition) from 41,000 to 39,000 years ago. Iberian Neanderthals possibly persisted until about 35,000 years ago, modern human expansion perhaps impeded by the Ebro River. Neanderthals in Gibraltar may have survived as late as 28,000 years ago at Gorham's Cave. The dating of these late Iberian sites is contested.

Historically, the cause of extinction of Neanderthals and other archaic humans was viewed under an imperialistic guise, with the superior invading modern humans exterminating and replacing the inferior species.

When sapiens began to expand and spread, he eliminated the other contemporary races [including Neanderthals] just as the white man drove out the Australian aborigines and the North American Indians.

— Ernst Mayr, 1950

The assimilation of Neanderthal populations into modern human populations had long been hypothesised with supposed hybrid specimens, and was revitalised with the discovery of archaic human DNA in modern humans. Similarly, the Châtelperronian industry of central France and northern Spain may represent a culture of Neanderthals adopting modern human techniques, via acculturation. Other ambiguous transitional cultures include the Italian Uluzzian industry, and the Balkan Szeletian industry.

Aside from competition with modern humans, Neanderthal extinction has also been ascribed to their low population as well as the resulting mutational meltdown, making them less adaptable to major environmental changes (specifically Heinrich event 4) or new diseases.

The admixture between modern humans and Neanderthals went in both directions. And, some of the late archaeological tool cultures of Neanderthal, which coincide with the arrive of modern humans in Europe, may reflect the increased brain plasticity of hybrid Neanderthal-modern human individuals.

Denisovans (named after the cave in the Altai where the type remains were discovered) probably existed from at least 285,000 years ago to about 25,000 years ago, general in Asia to the east of the Neanderthal range from Altai and Tibet to Southeast Asia, and overlapping with the Neanderthal range in the Altai region. High altitude adaptation DNA admixed from Denisovans are found in Tibetans. Trace levels of Denisovan admixture are found in mainland Southeast Asia and East Asia, and in island Southeast Asia up to the Wallace Line. Modern humans with Australian aboriginal ancestry or Papuan ancestry or Filipino negrito ancestry have substantial Denisovan ancestry (up to 6%) in addition to their Neanderthal ancestry (up to 2%). Presumably, the Denisovan-modern human admixture whose legacies exist in Australian aborigines, Papuans, Filipino negritos, and mainland Southeast Asians and East Asians must have occurred around the time of first contact between the first wave of modern humans in Asia around 50,000 to 75,000 years ago, and was then greatly diluted by subsequent waves of modern human migration west of the Wallace line in Asia. Also, Denisovans presumably went extinct within a thousand or two thousand years or so of first contact with modern humans (which took place much later in Tibet than almost everywhere else).

The exact path from Homo erectus to modern humans, Neanderthals, and Denisovans (and possibly other now extinct archaic species derived from Homo erectus) is a matter of ongoing investigation and debate.

Denisovan mtDNA diverged from that of modern humans and Neanderthals about 1,313,500–779,300 years ago; whereas modern human and Neanderthal mtDNA diverged 618,000–321,200 years ago. Krause and colleagues then concluded that Denisovans were the descendants of an earlier migration of H. erectus out of Africa, completely distinct from modern humans and Neanderthals.

However, according to the nuclear DNA (nDNA) of Denisova 3—which had an unusual degree of DNA preservation with only low-level contamination—Denisovans and Neanderthals were more closely related to each other than they were to modern humans. Using the percent distance from human–chimpanzee last common ancestor, Denisovans/Neanderthals split from modern humans about 804,000 years ago, and from each other 640,000 years ago. 

Using a mutation rate of 1×10^−9 or 0.5×10^−9 per base pair (bp) per year, the Neanderthal/Denisovan split occurred around either 236–190,000 or 473–381,000 years ago respectively. Using 1.1×10^−8 per generation with a new generation every 29 years, the time is 744,000 years ago. Using 5×10^−10 nucleotide site per year, it is 616,000 years ago. Using the latter dates, the split had likely already occurred by the time hominins spread out across Europe. 

H. heidelbergensis is typically considered to have been the direct ancestor of Denisovans and Neanderthals, and sometimes also modern humans. Due to the strong divergence in dental anatomy, they [i.e. Denisovans] may have split before characteristic Neanderthal dentition evolved about 300,000 years ago.

The more divergent Denisovan mtDNA has been interpreted as evidence of admixture between Denisovans and an unknown archaic human population, possibly a relict H. erectus or H. erectus-like population about 53,000 years ago. Alternatively, divergent mtDNA could have also resulted from the persistence of an ancient mtDNA lineage which only went extinct in modern humans and Neanderthals through genetic drift. Modern humans contributed mtDNA to the Neanderthal lineage, but not to the Denisovan mitochondrial genomes yet sequenced. The mtDNA sequence from the femur of a 400,000-year-old H. heidelbergensis from the Sima de los Huesos Cave in Spain was found to be related to those of Neanderthals and Denisovans, but closer to Denisovans, and the authors posited that this mtDNA represents an archaic sequence which was subsequently lost in Neanderthals due to replacement by a modern-human-related sequence.

The intermediate species that is the most recent common ancestor of Neanderthals, Denisovans, and modern humans probably arose not long after a genetic bottleneck which has been inferred from modern DNA. This genetic bottleneck probably occurred in the clade of H. erectus which is ancestral to modern humans. As one secondary source explaining this notes:

Between 930,000 and 813,000 years ago, something nearly ended humanity before it even began. A mysterious bottleneck reduced the human breeding population to just 1,280 individuals, pushing our ancestors to the brink of extinction for an astonishing 117,000 years. 

Scientists have long puzzled over a gap in the African and Eurasian fossil records, and now, a team of researchers may have found the answer. Using a groundbreaking method called FitCoal, they analyzed the genomes of 3,154 modern humans to reconstruct ancient population sizes. What they found was staggering. Nearly 99% of early humans vanished, likely due to extreme climate events such as glaciations, severe droughts, and the collapse of ecosystems.

The world was changing. Glaciation, extreme droughts, and collapsing ecosystems made survival nearly impossible. Food sources vanished, and so did most of our ancestors. Those who remained – just a tiny fraction of the original population – fought to endure in a harsh and unpredictable environment. 

But against all odds, they survived. And in doing so, they may have changed the course of human evolution forever. Scientists believe this bottleneck could have led to the merging of two ancestral chromosomes, forming what we now know as chromosome 2 – a key feature that separates modern humans from other primates.

Around 813,000 years ago, the climate began to shift. Our ancestors may have mastered fire, allowing them to cook food, stay warm, and fend off predators. Populations rebounded, and from that tiny group of survivors, the future of humanity was born. 

This discovery reshapes our understanding of human history, and raises new questions. Where did these survivors live? How did they overcome such extreme conditions? Did this struggle push human intelligence to evolve faster?

The paper that is the basis for this account is Wangjie Hu, et al., "Genomic inference of a severe human bottleneck during the Early to Middle Pleistocene transition" 381(6661) Science 979-984 (August 31, 2023). Its abstract materials state:

Editor’s summary 

Today, there are more than 8 billion human beings on the planet. We dominate Earth’s landscapes, and our activities are driving large numbers of other species to extinction. Had a researcher looked at the world sometime between 800,000 and 900,000 years ago, however, the picture would have been quite different. Hu et al. used a newly developed coalescent model to predict past human population sizes from more than 3000 present-day human genomes (see the Perspective by Ashton and Stringer). The model detected a reduction in the population size of our ancestors from about 100,000 to about 1000 individuals, which persisted for about 100,000 years. The decline appears to have coincided with both major climate change and subsequent speciation events. —Sacha Vignieri 

Abstract 

Population size history is essential for studying human evolution. However, ancient population size history during the Pleistocene is notoriously difficult to unravel. In this study, we developed a fast infinitesimal time coalescent process (FitCoal) to circumvent this difficulty and calculated the composite likelihood for present-day human genomic sequences of 3154 individuals. Results showed that human ancestors went through a severe population bottleneck with about 1280 breeding individuals between around 930,000 and 813,000 years ago. The bottleneck lasted for about 117,000 years and brought human ancestors close to extinction. This bottleneck is congruent with a substantial chronological gap in the available African and Eurasian fossil record. Our results provide new insights into our ancestry and suggest a coincident speciation event.

The proposed climate event was part of the Mid-Pleistocene Transition. Some key aspects of this, in places where Homo erectus reached, were as follows:

Europe

In Europe, the MPT was associated with the Epivillafranchian-Galerian transition and may have led to the local extinction of, among other taxa, Puma pardoides, Megantereon whitei, and Xenocyon lycaonoides. The prevalence of ungulates adapted for grazing increased in the Mediterranean region after the "0.9 Ma event". The northern North Sea Basin was first glaciated during the MPT. The increased intensity of transgressive-regressive cycles is recorded in northern Italy.

Asia

The cooling brought about by the MPT increased westerly aridity in the western Tarim Basin. East Asian Summer Monsoon (EASM) precipitation declined. Grasslands expanded across the North China Plain as forests contracted.

During the MPT, the Indian Summer Monsoon (ISM) decreased in strength. In the middle of the MPT, there was a sudden decrease in denitrification, likely due to increased solubility of oxygen during lengthened glacial periods. After the MPT, the Bay of Bengal experienced increased stratification as a result of the strengthening of the ISM, which resulted in increased riverine flux, inhibiting mixing and creating a shallow thermocline, with stratification being stronger during interstadials than stadials. Paradoxically, variability in Δδ18O in the Bay of Bengal between glacials and interglacials decreased following the MPT.

Africa

In Central Africa, detectable floral changes corresponding to glacial cycles were absent prior to the MPT. Following the MPT, a clear cyclicity became evident, with interglacials being characterised by warm and dry conditions while glacials were cool and humid.

According to one of the leading papers on the 0.9 Ma Event, closely associated with the Homo erectus genetic bottleneck:

The Early-Middle Pleistocene Transition (EMPT) (ca. 1.4–0.4 Ma) represents a fundamental transformation in the Earth's climate state, starting at 1.4 Ma with a progressive increase in the amplitude of climatic oscillations and the establishment of strong asymmetry in global ice volume cycles. The progressive shift from a 41kyr–100kyr orbital rhythm was followed by the first major build-up of global ice volume during MIS 24-22, the so-called “0.9 Ma event”. The Vallparadís Section (Vallès-Penedès Basin, NE Iberian Peninsula) is one of the few Pleistocene series in Europe that spans the onset of the transition (from 1.2 to 0.6 Ma), thus representing a pivotal array of localities to investigate the effect of glacial dynamics on environmental conditions in Southern Europe. Here we inspect the effects of the EMPT on terrestrial ecosystems by examining the dietary adaptations (through dental meso- and microwear patterns) of fossil ungulates from the Vallparadís Section dated before and after the “0.9 Ma event”. Results show a steady presence of open grasslands before MIS 22 and more humid conditions at MIS 21. Both before and after MIS 22, a consistent presence of ungulates with long-term patterns that point to a grazing or grass-rich mixed feeding behaviour is observed, while noticeably, short-term patterns point to increased seasonality right after the “0.9 Ma event” glacial period. This increment of seasonality may have had an important effect on the Mediterranean habitats leading to recurring changes in the quality of plant resources available to large herbivores, which in response periodically adopted more mixed feeding behaviours widening their dietary breadth to consume also sub-optimal food items during adverse seasons.

In particular, during this event, global ice volumes increased substantially, and the Northern Hemisphere experienced increased seasonality and aridity, and surface sea temperatures in the North Atlantic reached their lowest values during the EMPT at this time. Also, grasslands expanded across the North China Plain as forests contracted.

This hypothesis is model dependent, could be impacted by sources of systemic error, like the possible much later extinction of Homo erectus populations derived from the same source population, later hard genetic sweeps of Homo erectus source genes, the effective extinction of modern humans arising from other clades of Homo erectus at some much later time, a lack of consideration of Neanderthal or Denisovan genes in the analysis, and a complete lack of ancient Homo erectus genomes. 

Also, in understanding this narrative one has to recognize that genetics researchers call an "effective population" of 1,280 individuals could have involved a census population at any one time that was many times larger than that. And, this is still about five times as large as the effective population size of the founding population of the Americas, for example. So, the bottleneck wasn't quite as extreme as some popular accounts of it would imply.

But the oldest examples of the species Homo antecessor does first appear in Europe, shortly after this inferred bottleneck, and there are no Homo erectus remains in Europe during or after the time of this inferred bottleneck.

Homo antecessor (Latin "pioneer man") is an extinct species of archaic human recorded in the Spanish Sierra de Atapuerca, a productive archaeological site, from 1.2 to 0.8 million years ago during the Early Pleistocene. Populations of this species may have been present elsewhere in Western Europe, and were among the first to settle that region of the world, hence the name. The first fossils were found in the Gran Dolina cave in 1994, and the species was formally described in 1997 as the last common ancestor of modern humans and Neanderthals, supplanting the more conventional H. heidelbergensis in this position. H. antecessor has since been reinterpreted as an offshoot from the modern human line, although probably one branching off just before the modern human/Neanderthal split.

Despite being so ancient, the face is unexpectedly similar to that of modern humans rather than other archaic humans—namely in its overall flatness as well as the curving of the cheekbone as it merges into the upper jaw—although these elements are known only from a juvenile specimen. Brain volume could have been 1,000 cc (61 cu in) or more, but no intact braincase has been discovered. This is within the range of variation for modern humans. Stature estimates range from 162.3–186.8 cm (5 ft 4 in – 6 ft 2 in). H. antecessor may have been broad-chested and rather heavy, much like Neanderthals, although the limbs were proportionally long, a trait more frequent in tropical populations. The kneecaps are thin and have poorly developed tendon attachments. The feet indicate H. antecessor walked differently than modern humans.

H. antecessor was predominantly manufacturing simple pebble and flake stone tools out of quartz and chert, although they used a variety of materials. This industry has some similarities with the more complex Acheulean, an industry which is characteristic of contemporary African and later European sites. Groups may have been dispatching hunting parties, which mainly targeted deer in their savannah and mixed woodland environment. Many of the H. antecessor specimens were cannibalised, perhaps as a cultural practice. There is no evidence they were using fire, and they similarly only inhabited inland Iberia during warm periods, presumably retreating to the coast otherwise.

Meanwhile:

Homo heidelbergensis (also H. erectus heidelbergensis, H. sapiens heidelbergensis) is an extinct species or subspecies of archaic human which existed from around 600,000 to 300,000 years ago, during the Middle Pleistocene. Homo heidelbergensis was widely considered the most recent common ancestor of modern humans and Neanderthals, but this view has been increasingly disputed since the late 2010s.

In the Middle Pleistocene, brain size and height were comparable to modern humans. Like Neanderthals, H. heidelbergensis had a wide chest and robust frame.

Fire likely became an integral part of daily life after 400,000 years ago, and this roughly coincides with more permanent and widespread occupation of Europe (above 45°N), and the appearance of hafting technology to create spears. H. heidelbergensis may have been able to carry out coordinated hunting strategies, and consequently they seem to have had a higher consumption of meat.

It is debated whether or not to constrain H. heidelbergensis to only Europe or to also include African and Asian specimens, and this is further confounded by the type specimen (Mauer 1) being a jawbone, because jawbones feature few diagnostic traits and are generally missing among Middle Pleistocene specimens.

H. heidelbergensis was subsumed in 1950 as a subspecies of H. erectus but today it is more widely classified as its own species. H. heidelbergensis is regarded as a chronospecies, evolving from an African form of H. erectus (sometimes called H. ergaster).

At least three other archaic hominin species overlapped with hominins from the H. erectus era or later.

• Homo floresiensis – Extinct small human species found in Flores
• Homo luzonensis – Archaic human from Luzon, Philippines
• Homo naledi – South African archaic human species

H. floresiensis and H. luzonensis may have been regional variations of the same species and show similarities with each other. The most plausible theory of their phylogenetic position, in my view, is that both of them were sub-species of H. habilis, and may have left Africa, either independently, or together with either H. erectus, the Denisovan ancestor, or Denisovans themselves. H. floresiensis and Denisovans (and possibly the earliest modern humans to arrive there as well) may have co-existed on the island of Flores, Indonesia (which is past the Wallace line) at some point in  time. There are no remains of H. floresiensis, H. luzonensis, H. habilis, or any other archaic hominins before H. erectus disperses from Africa. 

H. naledi was a South African archaic hominin species that flourished from 335,000 to 226,000 years ago, that was probably not directly ancestral to modern humans or any other non-African archaic hominins, but would have co-existed in time (and possibly space) with the earliest modern humans in Africa.

A November 6, 2024 post at this blog recapped some other possible non-African archaic hominins who existed at the same time that modern humans did: 

Notably the remains of the Red Deer Cave People of China from 14,000 years ago (a few thousand years before the start of the Holocene era) are genetically modern humans and are not archaic hominins despite some of their seemingly archaic features. See also here.

I am also inclined to think that they may yet be a small relict population of small archaic hominins in a remote Indonesian jungle on the island of Sumatra and perhaps Flores as well, where these cryptids, called Orang Pendek, locally, have been attested but not definitively confirmed to still exist. I discuss this further at this post.

Homo floresiensis (discovered in 2003) are commonly known as "hobbits" and have been found on the island of Flores. Their phylogeny is disputed, but I find the theory that they are an asian branch of H. habilis to be most convincing. H. luzonesis (discovered in 2007) is similar and contemporaneous, but found further east in the Philippines and is supported by a less complete archaeological record. Both of these diminutive species are found in association with late Pleistocene tools and "oriental fauna".

Personally, being more of a lumper than a splitter, I'm inclined to see H. floresiensis and H. luzonesis as sub-species variations of the same species ("race" within that species to use some outdated terminology), and likewise to see H. longi, H. juluensis, and Denisovans as sub-species variations of the Denisovan species. The Hualongdong archaic hominin fossils ... could be a hybrid individual, perhaps a Neanderthal-Denisovan hybrid individual (something that has precedent in a Denisovan cave DNA sample).

Academic anthropologists, in contrast, tend to be splitters, in part, because it is cool and career advancing to discover and name your own archaic species, in part because the data is so fragmentary that grouping different fragmentary remains in a clade presumes relationships between the remains that aren't solidly proven, and in part, because it is easy to underestimate how much morphological diversity is possible within a single species if populations of it exposed to different environmental conditions.

H. longi a.ka. "dragon man" dates to an earlier time period (still contemporaneous with modern humans in Africa) in China and Manchuria, was discovered in 1933, and has been hypothesized to be a sister clade to Neanderthals, Denisovans, and modern humans, and a descendant of the pre-modern human hominin species H. antecessor due in part to basal archaic features in the skull.

H. juluensis (literally "big heads") is contemporaneous H. longi, and beyond that time frame into the time frame of H. floresiensis and was discovered from 1976-1979 in China and Tibet. The authors assign this specimen along with Xiahe and Penghu fossils, to the Denisovan species (a sister clade to Neanderthals and modern humans) based upon comparisons of their fossil teeth and rough geographic proximity. H. juluensis is found in association with early Paleolithic tools and remains of Paleoarctic fauna. But they have larger brain cases than H. longi. A previous suggestions of the link between H. longi and the Denisovan species are discussed here and here at this blog. At least one Denisovan tooth has been found in Laos dated to 131,000 years ago.

The article also discusses the Hualongdong archaic hominin fossils that "date to the late Middle Pleistocene (~300,000 years BP) and display a mosaic of characteristics that cannot be easily fitted into any one lineage," although they are closer to H. longi and H. juluensis. This individual could be a hybrid between these two subspecies, with H. erectus, or with a Neanderthal who was far east of his usual range.

Prior to 2021, H. longi and H. juluensis tended to be classified as H. erectus (remains of which start to appear at a much greater time depth in Asia) or as archaic modern humans.

The Narmada and Maba partial skulls, especially the latter, are suggestively associated with Neanderthals by the article.

These Asian archaic species also overlap in time with the Southern African archaic hominin clade H. naledi which is a sister clade to the modern human ancestors and to the common ancestor of modern humans, Neanderthals, and Denisovans, but is not actually among our ancestors. As I explained at the link, this species "is basically a story from The Silmarillion of hominin evolution. It is entertaining, especially for hard core human evolution fans, but it doesn't really advance the plot."

A small number of papers reported genetic evidence in modern Africans of admixture with an archaic hominin "ghost species" in Africa, but subsequent papers have explained this "ghost species" signal as a methodological artifact that merely arises from population structure in early modern human Africans (see also here). But there may have been relict archaic hominins that did not admix with modern humans in Africa that were also contemporaneous with modern humans, at least, early on.

The question of whether behaviorally modern humans started showing advanced behavior around 70,000-50,000 years ago (at the dawn of the Upper Paleolithic era and close in time to the Out of Africa event for modern humans), was associated with an evolutionary leap in their brains is an open and unresolved question. See also here (addressing the question of what made modern humans genetically distinct from archaic hominins).