Gendered division of labor gave modern humans advantage over Neanderthals
Diversified social roles for men, women, and children may have given Homo sapiens an advantage over Neanderthals, says a new study in the December 2006 issue of Current Anthropology. The study argues that division of economic labor by sex and age emerged relatively recently in human evolutionary history and facilitated the spread of modern humans throughout Eurasia.
“The competitive advantage enjoyed by modern humans came not just from new weapons and devices but from the ways in which their economic lives were organized around the advantages of cooperation and complementary subsistence roles for men, women, and children,” write Steven L. Kuhn and Mary C. Stiner (University of Arizona).
Kuhn and Stiner note that the rich archaeological record for Neanderthal diets provides little direct evidence for a reliance on subsistence foods, such as milling stones to grind nuts and seeds. Instead, Neanderthals depended on large game, a high-stakes resource, to fuel their massive body mass and high caloric intake. This lack of food diversity and the presence of healed fractures on Neanderthal skeletons—attesting to a rough-and-tumble lifestyle—suggest that female and juvenile Neanderthals participated actively in the hunt by serving as game drivers, beating bushes or cutting off escape routes.
The Middle Paleolithic Neanderthal record also lacks the artifacts commonly used to make weather-resistant clothing or artificial shelters, such as bone needles. Thus, it was the emergence of “female” roles – subsistence and skill-intensive craft – that allowed H. sapiens in ecologically diverse tropical and sub-tropical regions to take advantage of other foods and live at higher population densities.
“Earlier hominins pursued more narrowly focused economies, with women’s activities more closely aligned with those of men with respect to schedule and ranging patterns,” write the authors. “It is impossible to argue that [Neanderthal] females and juveniles were fulfilling the same roles—or even an equally diverse suite of economic roles—as females and juveniles in recent hunter-gatherer groups,” they add.
While some degree of niche specialization between adult male and females is documented for many large-mammal species, recent humans are remarkable for cooperative economies that combine pervasive sharing and complementary roles for individuals of different ages and sexes.
Well, something suddenly gave modern humans the edge. Prior to about 40,00 years ago we couldn’t penetrate Neanderthal-dominated Europe. In circumstances where two groups are competing over the long term, even a 1% advantage can be the cause of one group overwhelming another.
Certainly, stopping females of reproductive age getting in the way of danger is good idea, as a tribe’s reproductive future is totally dependent on how many breeding females it has (you can get by with a lot fewer males). Female Neanderthals seemed to join in the hunt, judging by the kinds of injuries they sustained.
Modern humans also seemed to have a much wider diet, always a good call in any circumstance. If the hunt fails, there will still be nuts and berries to tide you over.
Assuming each group has a stable population to start with (2 surviving children per woman)… Let’s assume modern humans had a survival advantage of 1% for their children, starting with a population of 10,000; this would translate as a population growth of.. ( I hope my maths is right)
- 10,415 (100 years)
- 10,945 (200 years)
Assuming that the area can only support 20,000 people, population B will find itself down to 9585 people, in just 100 years (five average generations). Over a few thousand years, this would effectively wipe out the Neanderthals. Even a very slight advantage will win out in a time scale of tens of thousands of years.
There’s also the possibility that modern humans were just a bit sharper mentally too, or became so about the point they began to expand into Neanderthal territory. The likelihood of this been a ‘single gene’ trait is probably very slim, as polygenic traits like intelligence don’t pass along easily into new populations. It’s much easier for the new population who have all the genes to just expand. There does seem to be a small technology boom about the time of the modern human expansion into Europe, adding weight to the increased intelligence theory.
None of this excludes that Neanderthals contributed something to the gene pool, it just means that they were most likely a small minority contributor, and that it would mostly have been female mediated- a standard pattern in a people who are being wiped out. The lack of any Neanderthal Y chromosomes isn’t any kind of a surprise, as one South American country couldn’t find any native Y chromosomes to be found in one Y DNA study.
Add to this that any half-Neanderthal children wouldn’t have had the full set of intelligence increasing/behaviour modifying genes, putting them at a disadvantage to the all modern human offspring, and you’re looking at a dwindling contribution yet again. And, at a later date, another modern human population swept into Europe from the SE, almost totally replacing the hunter gatherers of the Mesolithic in places like Bulgaria and Greece.
Repeated waves of expanding human populations that nearly entirely replace the prior occupants of an area seem to be the norm in human evolution, it’s just that the Neanderthals were so long ago we are only finding faint traces of them in DNA studies that show ancient genes in Eurasia with non-African origin.