Ancient DNA and Neanderthals

DNA can be used to understand aspects of biology and evolution, the fact that DNA is a fragile molecule and decays over time has made it difficult to use DNA to learn more about extinct species. After decades of work, scientists can now use ancient DNA to understand aspects of the biology of our closest extinct relatives, the Neanderthals (Homo neanderthalensis) such as their appearance, physiology, speech capability, and population structure, as well as their phylogenetic relationship with modern humans, our own species (Homo sapiens).The Neanderthal and modern human lineages probably began to diverge about 500,000 years ago, with the ancestral population to Neanderthals traveling to Europe and the Middle East and the ancestral population to modern humans remaining in Africa for roughly another 400,000 years. Neanderthals had plenty of time to develop cold-weather adaptations to allow their bodies to retain as much heat as possible in the frigid European climates. Their bodies were stockier and their limbs slightly shorter and more robust than their modern human counterparts. Despite this difference, Neanderthals and modern humans looked very similar and occupied similar ecological niches when their habitats overlapped. One question remains central to the study of Neanderthals and modern humans, if we were so similar, why did the Neanderthals become extinct and while modern humans thrived?