Researchers find that humans have changed significantly in just the past 1,500 years or so.
Scientists researching the evolution of earthly life aren't just looking in a rearview mirror. Evolution through natural selection, which has shaped the biological world, is active today. It guides the adaptation of plants and animals to climate change. It affects the way endangered species respond to conservation programs. It is changing the human species in unsuspected ways.
New data on the accumulation of recent mutations in the human genome upends the standard assumption that modern humans have evolved little since they emerged from Africa some 40,000 years ago. Instead, team leader Henry Harpending at the University of Utah in Salt Lake City says the data indicate that "humans are evolving rapidly and that the pace of change has accelerated a lot in the last 40,000 years, especially since the end of the Ice Age roughly 10,000 years ago." He adds, "We aren't the same as people even 1,000 or 2,000 years ago."
Professor Harpending and colleagues at several other universities are tracking the occurrence of simple point mutations along the genomes of specific individuals. The data include 3.9 million of these mutations in 270 people from Han Chinese, Japanese, African Yoruba tribe, and northern European populations. The Europeans are represented largely by Utah Mormons.
These are limited data. Yet, as a first cut at tracking contemporary human evolution, they indicate a surprising trend. The human groups on different continents are moving away from each other genetically, not mixing together. One of the team's key findings, reported last month in the online Proceedings of the National Academy of Sciences, is that 7 percent of human genes are undergoing rapid evolution.