Asian Monsoon Rains Drove the Evolution of Mammals

Asian monsoon rains may have driven evolution in mammals. Scientists have taken a closer look at the South Asian monsoon and have found that it may have been a major contributor to how mammals look and act today in the region.

In this latest study, the scientists examined the pattern of variation in the south Asian monsoon over time and compared it with the evolution of African mole rats and bamboo rats. They analyzed the rats' relationships in addition to their distribution in space and through time; they also examined their evolutionary rates.

"We used rodents in this study because they are the most common mammals in the fossil record, and they evolved rapidly and are very sensitive to any changes in their habitat," said Fabien Knoll, a senior researcher, in a news release.

The scientists examined the changes in teeth and head shape of the rodents over a period of 24 million years. They also examined the strengthening and weakening of the monsoon during this time period. Of the 38 species studied, only six still exist today; not only that, but the changing rains seem to have driven several of these species to extinction.

"It was natural to assume that a mighty climatic phenomenon like the monsoon would play a part in evolution, but until now there has never been any decisive evidence thereof," said Knoll.

The scientists found that in periods when the monsoon was weaker, the rodents' teeth changed, as did other body parts they used for digging. Being able to dig would have provided the rodents with resources as well as protection from predators when the forest cover was thinner.

"We suggest that the variations in the monsoon intensity have impacted the evolution of most, if not all, mammals living in this region, although this remains to be proved convincingly (using our methodology or others) and the pattern would probably vary from group to group," write the researchers.

The findings are published in the journal Scientific Reports.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).