In most places where agriculture was adopted, it replaced hunting and foraging. But, new hard evidence based upon isotypes in small mammal bones in Papua New Guinea demonstrates that there, foraging remained an important source of subsistence until at least 300 years ago. As a Science Daily press release explains:
In tropical New Guinea, where one of the earliest human experiments with agriculture occurred, agriculture apparently never replaced foraging as a primary subsistence strategy: "Montane tropical forest environments provided a stable source of subsistence for human hunter-gatherers in New Guinea," says Patrick Roberts, primary author of the study. "We have found out that foragers were living in close proximity to emerging farming groups, from 12,000 to 300 years ago, which indicates that agriculture was not a forced event in this part of the world."
Tropical forests have frequently been perceived as unattractive habitats for humans -- both foragers and farmers -- due to poor soils, difficulties of humidity, and issues of reliable nutrition. However, archaeological work in New Guinea, among other tropical regions, has now helped to refute this idea: "We can now affirm that humans have occupied areas in this region, covered today in rainforest, from 45,000 years ago," says..., Professor Glenn Summerhayes from the University of Otago, senior author of the study. "Some of the earliest evidence for the human development of agriculture comes precisely from the tropical forested portions of New Guinea."
This is particularly notable, because most cultures in global history that have been slow adopters of agriculture have had a predominantly fishing based economy as an alternative, but in New Guinea we have a group of terrestrial hunter-gatherers in a tropical forest instead.
The abstract and citation to the source article are as follows:
The terminal Pleistocene/Holocene boundary (approximately 12–8 thousand years ago) represented a major ecological threshold for humans, both as a significant climate transition and due to the emergence of agriculture around this time. In the highlands of New Guinea, climatic and environmental changes across this period have been highlighted as potential drivers of one of the earliest domestication processes in the world. We present a terminal Pleistocene/Holocene palaeoenvironmental record (12–0 thousand years ago ) of carbon and oxygen isotopes in small mammal tooth enamel from the site of Kiowa. The results show that tropical highland forest and open mosaics, and the human subsistence focused on these environments, remained stable throughout the period in which agriculture emerged at nearby Kuk Swamp. This suggests the persistence of tropical forest foraging among highland New Guinea groups and highlights that agriculture in the region was not adopted as a unilinear or dramatic, forced event but was locally and historically contingent.
Patrick Roberts, Dylan Gaffney, Julia Lee-Thorp, and Glenn Summerhayes. "Persistent tropical foraging in the highlands of terminal Pleistocene/Holocene New Guinea." 1 Nature Ecology & Evolution 44 (2017).