There are clear indicators to this conclusion

Nov 14, 2009 08:35 GMT  ·  By

For many years, a large number of scientists have argued that human evolution may have come to a standstill, and even that we may be regressing. These ideas were mostly founded on the lack of observable evidence to support the claim that we were still moving ahead on the evolutionary ladder. More recent data pointed out, however, that these experts did not know where to look for the proper evidence. One thing that proved that evolution continued, and even accelerateed, was the fact that, over the past 5,000 years, our brains appeared to had been shrinking constantly.

Our genomes also show evidence of significant changes, recorded over the past 10,000 years. This is the same time when agriculture – and, therefore, a more modern lifestyle – began, and there are some researchers who say that the two events are related. Several hundred genes have evolved, either for good or for bad, during this time frame. Some geneticists say that something as simple and common as lactose intolerance may also be a sign of evolution. “We know the brain has been evolving in human populations quite recently,” University of Wisconsin-Madison (UWM) paleoanthropologist John Hawks explains, quoted by LiveScience.

“When it comes to recent evolutionary changes, we currently maybe have the least specific details with regard [to] the brain, but we do know from archaeological data that pretty much everywhere we can measure – Europe, China, South Africa, Australia – that brains have shrunk about 150 cubic centimeters, off a mean of about 1,350. That's roughly 10 percent. As to why is it shrinking, perhaps in big societies, as opposed to hunter-gatherer lifestyles, we can rely on other people for more things, can specialize our behavior to a greater extent, and maybe not need our brains as much,” the expert adds.

He also explains that evolution can also be seen in the way our bodies adapted to fighting diseases such as malaria. Because the condition affects people early in life, there was a lot of pressure on humans to develop defense mechanisms, which would have allowed them to reproduce. Biologists believe that this may be the main reason why sickle cell anemia appeared. When this condition sets on, red blood cells take on a sickle shape, which impairs blood flow, but also prevents malaria from infecting the human body and developing.

“Although sickle cell is best known in Africa, there is also an India-Pakistan variant of it that seems to have evolved separately. Both variants have evolved very recently, in the last three or four thousand years, and in that time have risen to as much as 10 to 15 percent of the populations. That's pretty rapid change,” Hawks adds. Similar genetic changes are also visible against type II diabetes. The expert explains that it's absolutely necessary for the human body to adapt to an agricultural diet, and that this type of diet is fairly new. About 10,000 years is a very short time for genetic traits to develop.

“The ecology of humans has been changing. The biggest changes have to do with agriculture and its consequences – dealing with a new subsistence pattern that caused people to rely on foods that were never very important before, a radical shift from hunter-gatherer diets. For instance, agricultural populations tend to have more copies of a gene for salivary amylase, which helps them digest starch,” Hawks concludes.