According to some recent articles in Scientific American magazine, biologists recently discovered that humans have gone through a lot of evolutionary changes in just the last 10,000 years. By comparing DNA from people around the globe and compared recent DNA to those of human remains from centuries ago, scientists found that at least 7 percent of human genes underwent evolution as recently as 5,000 years ago. This is fascinating, because we don't see as much evolutionary change in the preceding 200,000 years before that. We are evolving at a rate 100 times faster than any time since we split off from the chimpanzees 5 million years ago. Many of the recent genetic changes are in genes related to diet, brain structures or immunity. The changes related to immunity makes sense in if you consider that humanity has come into increased contact with animals (cows, goats, chickens, etc...) and that people with robust immune systems are likely to survive and reproduce. Furthermore, by living in cities more and more often over the last 10 thousand years, humans have become exposed to open sewage. As for genetic changes related to brain structures, I guess that means smarter people were more likely to pass on their genes than those with below average intelligence. Genes which regulate dietary metabolism changed a lot because we now eat foods which our ancestors never dreamed of. (e.g. - cheese, breads, rice, high fructose corn syrup, etc....) Now, we also know that humans have a larger penis compared to our primate relatives, the gorillas, chimpanzees, and bonobos. We've got larger penises both in terms of absolute size and compared to overall body size. However, we have no idea when large penises evolved among our ancestors. To put it bluntly, there are no penises in the fossil record - just hard body parts like bones and teeth. (Yeah, we like to brag about the hardness of our cocks, but compared to really tough parts like bones and teeth, penises just don't compare.) Upon learning how many genes have changed in human history over the last 10,000 years, we can now speculate that the enlargement of human penises occurred recently. It is quite possible that during the last ice age, the average penis was a mere 4 inches or less. The last ice age ended between 10,000 and 15,000 before present. Perhaps since then, the average penis size extended to 6 inches. If true, that merely means that men with longer penises were more likely ot bear offspring than men with shorter organs. In a few years, we might be able to determine if genes related to penis size did change within the last 10 thousand years, or if they remain unchanged since before then. Once humans identify which genes affect penis size, we can then compare those genes among different humans alive today and among those in the fossil record to see how recently they changed. The scientific field of molecular evolution provides techniques for determining how long ago a gene may have changed. Indeed, the molecular clock within our DNA has already surprised us with the revelation about how fast we are changing. This line of thinking leads to various questions. Did human penis size really increase that much within historical times? Will the human penis size continue to increase over hundreds of future generations? What factors led to humans having a much larger organ than our ape cousins?