Topic: Research News
Scientists studied newborn babies' fingers and found a link between estrogen exposure before birth and brain size. The study suggests that higher estrogen levels may have contributed to human brain evolution.
Human evolution is closely linked to the development of a larger brain. Researchers at Swansea University, led by Professor John Manning, explored how prenatal hormones might have influenced this process. They focused on digit ratio, which compares the length of the index finger (2D) with the ring finger (4D). This measurement, called the 2D:4D ratio, can indicate the balance of estrogen and testosterone a fetus was exposed to during pregnancy.
The team measured the 2D:4D ratios of 225 newborn babies, including 100 boys and 125 girls. They also recorded each baby's head circumference, which is often used as an indicator of brain size in newborns. The researchers found that boys with higher 2D:4D ratios tended to have larger head circumferences.
This study supports the estrogenized ape hypothesis, which proposes that human brain evolution was linked to changes making the human skeleton less robust and more feminine compared to earlier ancestors. Professor Manning said,
Implications
Scientists studied newborn babies' fingers and found a link between estrogen exposure before birth and brain size. The study suggests that higher estrogen levels may have contributed to human brain evolution.
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