A team of international scientists used Neanderthal teeth from 250,000 years ago to figure out how ancient climates have affected human evolution. 

In a new study, experts hailing from North America, Europe, and Australia found that Neanderthal children have endured extreme cold weather. They also found that the Neanderthal who once owned the teeth has been exposed to lead. 

The findings were published in the journal Science Advances on Thursday, Nov. 1. 

The Stories Neanderthal Teeth Tell

The team of researchers examined thin sections of teeth from two Neanderthals recovered from an archeological site in southeastern France. They also had teeth sample from one modern human that lived about 5,000 years ago. The samples were able to record up to three years of the children's life. 

While small, teeth reveal a lot about a person. Like tree rings, teeth enamel form layers that contain chemical traces from a person's life. 

To examine these layers, the researchers used sensitive high-resolution ion microprobe (or SHRIMP) that reveals information of oxygen variation influenced by the weather or a person's diet. 

"This allowed us to relate their development to ancient seasons, revealing that one Neanderthal was born in the spring, and that both Neanderthal children were more likely to be sick during colder periods," stated Tanya Smith of Griffith University's Australian Research Center for Human Evolution.

Scientists have long known that Neanderthals thrived through the frigid cold in Europe. However, the new study provides a look at the direct effect of the very cold winter months to the group. 

From one of the teeth, the researchers found that one of the children experienced sickness and starvation for about a week at 1 year of age. The other child also probably experienced the same for two weeks during winter and one week during fall. 

Lead Traces On Teeth

The team of researchers also measured the presence of barium and lead from the teeth. Barium is the marker for milk consumption and traces of it in the teeth tells that the Neanderthal children were nursed until they were 2.5 years old.

Neanderthal moms nursed their children through the frigid cold or when they were sick. This suggests that Neanderthal mom took care of their children as intensely as modern moms do now. 

The presence of lead, however, meant that the Neanderthal children have accidentally ingested the chemical from contaminated food and water from a nearby mine. This is also the oldest recorded lead exposure in any hominin. 

"These techniques help us build more nuanced pictures of what their lives were like season to season," stated Katie Hinde of Arizona State University. "This gives us insight into the origins of health and disease and let us understand more about the environments that shape humans and our close relatives."

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