Scientists looked at how cultural influences like easy access to contraception and medical advances reducing infant mortality, effects natural selection
in modern human populations.
The authors of the study, an international team from Portuguese, Spanish, Catalonian, German, Austrian and Italian research institutions, say their findings suggest that the process
of modern human populations absorbing Neanderthal populations through interbreeding was not a regular, gradual wave - of - advance but a «stop - and - go, punctuated, geographically uneven history.»
But the need for pigment to provide this extra protection waned as
modern human populations migrated northward over the past 60,000 years or so, while the need to absorb UVB light became greater, particularly for those humans who migrated to the far North behind retreating glaciers less than 10,000 years ago.
But the need for pigment to provide this extra protection waned
as modern human populations migrated northward over the past 60,000 years or so, Elias said, while the need to absorb UVB light became greater, particularly for those humans who migrated to the far North behind retreating glaciers less than 10,000 years ago.
Rapid climate change during the Middle Stone Age, between 80,000 and 40,000 years ago, during the Middle Stone Age, sparked surges in cultural innovation in
early modern human populations, according to new research.
«We're looking at a very interesting population scenario» — one that does not jibe entirely with what we thought we knew about how
waves modern human populations migrated into and through Asia and out to Oceania's islands.
«This is reassuring if we want to use current patterns of natural selection and genetic variation to make predictions of what will happen in
modern human populations over the next few generations,» added Dr Bolund.
That, says Theodore Schurr, an anthropologist at the University of Pennsylvania, «lends credence to the reemerging hypothesis that the
first modern human populations to arrive in North America and then populate the rest of the Americas used a coastal route to actually get there.»
Still, I find it fascinating to think that if the Neanderthals had reached larger population sizes in Europe, or
if modern human populations had grown slower, some of us today would probably carry a lot more Neanderthal ancestry in our genome.»
But Fred Spoor, at University College London, UK, disputes this interpretation, saying there is probably similar variation
among modern human populations and ape species.
By aligning the Denisovan genome with that of the reference human genome and counting mutations, the team calculated that the Denisovan and
modern human populations finally split between 170,000 and 700,000 years ago.
This interbreeding is estimated to have happened less than 65,000 years ago, around the time that
modern human populations spread across Eurasia from Africa.
Neanderthal DNA from a femur offers scientists proof that a small human group left Africa and disappeared long before the ancient human migration that
spearheaded modern human population.
Results of the genome analysis, which was published in journal Nature on June 18, provided evidence that the Kennewick Man is more closely related to modern Native Americans compared with any other modern human populations
As Condemi and her colleagues wrote, the mandible supports the theory of «a slow process of replacement of Neanderthals by the
invading modern human populations, as well as additional evidence of the upholding of the Neanderthals» cultural identity.»
Sometime between 50,000 and 40,000 years ago,
anatomically modern human populations, Homo sapiens, entered the Levant from Africa and began branching East and West possibly encountering Neanderthal populations.
Working from the genetic sequences and their revised model, the researchers gleaned new insights into how Neanderthal, Denisovan and
modern human populations grew, shrank, separated and periodically merged through prehistory.
Supporters of the multiregional theory contend that
modern human populations developed independently from archaic hominid (Homo erectus or Homo ergaster) populations in Africa, Europe, and Asia.
As for why the percentage of Neanderthal DNA in some modern humans still appears to be so low, Kelso explained that there was selection against such genes in
early modern human populations.
The researchers suggest that some Neanderthal genetic variants might have provided benefits
in modern human populations as they first moved out of Africa thousands of years ago.
She is the author of Dancing Skeletons: Life and Death in West Africa 1993, and the co-editor of Breastfeeding: Biocultural Perspectives (1995), which includes her chapters «Beauty and the Breast: The Cultural Context of Breastfeeding in the United States,» and «A Time to Wean: The Hominid Blueprint for a Natural Age of Weaning in
Modern Human Populations.»
«The initial dispersals out of Africa prior to 60,000 years ago were likely by small groups of foragers, and at least some of these early dispersals left low - level genetic traces in
modern human populations.
According to Prof. Hershkovitz, the skull disproves two major narratives: that
all modern human populations are linked to migrations out of Africa 100,000 years ago, and that early European Upper Paleolithic populations interbred with local European Neanderthals.
Curiously, the researchers noted in their paper, the Denisovan population shows «a drastic decline in size at the time when
the modern human population began to expand.»
The team is now exploring just how widespread this retroviral DNA is in
the modern human population and whether the viruses themselves are ever active.
At the University of New Mexico in Albuquerque, genetic anthropologists Jeffrey Long, Keith Hunley, and Sarah Joyce used computers to analyze genetic data from 2,000 people in 100
modern human populations in Africa, Europe, Asia, Oceania, and the Americas.
Previous work has also shown that, following hybridization, many Neanderthal gene variants were lost from
the modern human population due to selection.
For tens of thousands of years after their emergence (anatomically),
modern human populations in Africa continued to use technologies that differed little from those of the non-modern populations that preceded them or that inhabited other regions both inside and outside the African continent.
Studying the genetics of
modern human populations, he and his colleagues stumbled across a region of the X chromosome, called RRM2P4, that shows large differences between people in different places — a sign of an ancient genetic split.
The haplogroup was probably beneficial enough to spread quickly in
modern human populations, says Lahn.
Neanderthals went extinct, or were absorbed into
the modern human population, about 32,000 years ago.
As for what happened to the Neanderthals, some researchers believe that they were simply absorbed into
the modern human population.
Gould reexamined Morton's data on cranial capacity variation in
modern human populations and concluded that Morton had selectively reported data (see Box 1), manipulated sample compositions (see Box 2), made analytical errors, and mismeasured skulls in order to support his a priori views on intelligence differences between human groups.
Recent evolutionary history of cats parallels that of
modern human populations, particularly the recently urbanized indigenous populations that have very high incidences of insulin resistance and diabetes.