A new study led by the University of Wisconsin-Madison
anthropologist John Hawks revelead that we are evolving faster then our
ancestors.
Based on the data from International HapMap Project, short
for haplotype mapping, Hawk concluded that the last 40,000 years from the human
history were a period of supercharged evolutionary change.
HapMap Project final goal is to catalog genetic similarities
and differences in human beings by studying genes from distinct sample
populations around the globe. While the HapMap will ultimately be used to
identify genes that affect human health, it can also provide a road map of
genetic variation from the ancestral human population.
According to Hawks, the exponential population growth and
cultural shifts were identified as the factors, which forced the humans to change
and evolve.
In his study published in the Dec. 10 issue of the
Proceedings of the National Academy of Sciences (PNAS), Hawks estimated that
positive selection just in the past 5,000 years alone — around the period of
the Stone Age — has occurred at a rate roughly 100 times higher than any other
period of human evolution.
“In evolutionary terms, cultures that grow slowly are at a
disadvantage, but the massive growth of human populations has led to far more
genetic mutations,” says Hawks. “And every mutation that is advantageous to
people has a chance of being selected and driven toward fixation. What we are
catching is an exceptional time.”
According to Hawks, we are more different genetically from
people living 5,000 years ago than they were different from Neanderthals.
Hawks has presented two examples to sustain the fact that the
genetic changes are now being driven by major changes in human culture.
Lactase, the gene that helps people digest milk declines and
stops activity about the time one becomes a teenager but northern Europeans
developed a variation of the gene that allowed them to drink milk their whole
lives — a relatively new adaptation that is directly tied to the advance of
domestic farming and use of milk as an agricultural product.
But the biggest new pathway for selection relates to disease
resistance, Hawks says.
Because epidemic diseases such as malaria, smallpox and
cholera began to dramatically shift mortality patterns in people, the humans
developed new genetic adaptations to survive.
Malaria is one of the clearest examples, Hawks says, given
that there are now more than two dozen identified genetic adaptations that
relate to malaria resistance, including an entirely new blood type known as the
Duffy blood type.
Another recently discovered gene, CCR5, originated about
4,000 years ago and now exists in about 10 percent of the European population.
It was discovered recently because it makes people resistant to HIV/AIDS. But
its original value might have come from obstructing the pathway for smallpox.
“There are many things under selection that are making it
harder for pathogens to kill us,” Hawks says.
