Jason Klass
Staff Writer
Approximately 8,000 years ago, right alongside the agricultural revolution, there was another revolution going on involving reproductive success. At this time, there was a sudden, extreme drop in the amount of men who would reproduce successfully, meaning that the children they had would continue to reproduce and a modern person would be able to trace their ancestors back to them.
More interestingly, this change wasn’t mirrored among women during the same time period. Reproductive success rates had been improving for thousands of years for both sexes before this heredity drought occurred. As a result of the start of agrarian civilization around the world, socioeconomic factors had a much larger influence on the likelihood of reproduction compared to natural selection.
By comparing 456 geographically diverse high-coverage Y chromosome sequences, including 299 newly reported samples and applying ancient DNA calibration, researchers discovered that there was a very strong bottleneck in Y-chromosome lineages dating to the last 10,000 years. Their findings were published in the Genome Research journal on March 13, 2015.
“Men who had more wealth and power might have had more to offer to women,” said co-author Melissa Wilson Sayres, an Arizona State University professor who studies sex-biased biology. “Their sons and grandsons could have been more successful in the same way.”
The semblance of prosperity, therefore, could have been a bigger genetic factor than natural selection, the researchers found. As farming civilizations developed, the successful civilizations were those with a greater amount of men successfully reproducing. Either they become more egalitarian, or the wealthy and powerful became more monogamous.
“This difference in reproductive rates probably shrank the pool of genetic traits that are passed down from men,” Wilson Sayres said, while boosting the mix of female-inherited characteristics. As Francie Diep at Pacific Standard writes, “As more thousands of years passed, the numbers of men reproducing, compared to women, rose again.”
Far from being robots who are acting out unchanging genetic scripts, we are creatures who experience periods of dramatic change—and those changes, in turn, change our genes. The real takeaway here is to be skeptical of the notion that our sexual and social habits are as strongly genetically programmed as some may believe. If a small percentage of people are able to leverage quickly gained power over a population of people again, similar events could happen.
More interestingly, this change wasn’t mirrored among women during the same time period. Reproductive success rates had been improving for thousands of years for both sexes before this heredity drought occurred. As a result of the start of agrarian civilization around the world, socioeconomic factors had a much larger influence on the likelihood of reproduction compared to natural selection.
By comparing 456 geographically diverse high-coverage Y chromosome sequences, including 299 newly reported samples and applying ancient DNA calibration, researchers discovered that there was a very strong bottleneck in Y-chromosome lineages dating to the last 10,000 years. Their findings were published in the Genome Research journal on March 13, 2015.
“Men who had more wealth and power might have had more to offer to women,” said co-author Melissa Wilson Sayres, an Arizona State University professor who studies sex-biased biology. “Their sons and grandsons could have been more successful in the same way.”
The semblance of prosperity, therefore, could have been a bigger genetic factor than natural selection, the researchers found. As farming civilizations developed, the successful civilizations were those with a greater amount of men successfully reproducing. Either they become more egalitarian, or the wealthy and powerful became more monogamous.
“This difference in reproductive rates probably shrank the pool of genetic traits that are passed down from men,” Wilson Sayres said, while boosting the mix of female-inherited characteristics. As Francie Diep at Pacific Standard writes, “As more thousands of years passed, the numbers of men reproducing, compared to women, rose again.”
Far from being robots who are acting out unchanging genetic scripts, we are creatures who experience periods of dramatic change—and those changes, in turn, change our genes. The real takeaway here is to be skeptical of the notion that our sexual and social habits are as strongly genetically programmed as some may believe. If a small percentage of people are able to leverage quickly gained power over a population of people again, similar events could happen.