https://humanorigins.si.edu/evidence/genetics/ancient-dna-a…

Ancient DNA and Neanderthals
DNA (deoxyribonucleic acid) is arguably one of the most useful tools that scientists can use to understand living organisms. Our genetic code can tell us a lot about who we are, where come from, and even what diseases we may be predisposed to contracting and acquiring. When studying evolution, DNA is especially important in its application to identifying and separating organisms into species. However, DNA is a fragile molecule, and it degrades over time. For most fossil species, there is essentially no hope of ever acquiring DNA from their fossils, so answers to questions about their appearance, physiology, population structure, and more may never be fully answerable. For more recently extinct species scientists have, and continue to, extract ancient DNA (aDNA) which they use to reconstruct the genome of long-gone ancestors and relatives. One such species is Neanderthals, Homo neanderthalensis.
Neanderthals were the first species of fossil hominins discovered and have secured their place in our collective imagination ever since. The first Neanderthal fossils were found in Engis, Belgium in 1829, but not identified as belonging to Neanderthals until almost 100 years later. The first fossils to be called Neanderthals were found in 1856 in Germany, at a site in the Neander Valley (where Neanderthals get their name from). Neanderthals diverged from modern humans around 500,000 years ago, likely evolving outside of Africa. Most ancestors of Homo sapiens remained in Africa until around 100,000 years ago when modern humans began migrating outwards. In that time, Neanderthals evolved many unique adaptations that helped them survive in cold environments of Europe and Asia. Their short limbs and torso help conserved heat, and their wide noses helped warm and humidify air as they breathed it in. Despite these differences, modern humans and Neanderthals are very closely related and looked similar. We even overlapped with each other-living in the sa…