Humans may not have lived with dinosaurs, but they did once share the Earth with creatures very similar to us. Neanderthals, or homo neanderthalensis, shared the planet with us until about 40,000 years ago. Despite them having died out millennia ago, archaeologists are still finding evidence of their existence, and learning more about what their lives were like, and how they related to us. Some things that we do know are that they were very similar to us intellectually, with practices such as wearing clothes and having burial rites, and that they coexisted with us for some time.
One of the biggest questions about Neanderthals is whether or not they were a distinct species, or if they were just a subspecies of humanity. The current view of the scientific community is that they are a distinct species, and that they and humans both evolved from homo erectus, an ancestor that existed in Africa hundreds of thousands of years ago. This conclusion was largely reached by analyzing Neanderthal DNA and comparing it to Human DNA.
Of course, that raises the question of how exactly we have intact DNA from a species that went extinct 40,000 years before we even knew DNA was a thing. The answer is that tiny amounts of DNA can persist in the core of fossilized bone, and thankfully we’ve found a substantial number of fossils from Neanderthals. The first to be discovered wasn’t immediately recognized as being from a distinct species — after all, it was the first evidence we had of there being another hominid species in our planet’s history — but analysis of the structure of its skull found it to be so distinct from modern humans that it had to be a different species.
Since then, we’ve found out more and more about Neanderthals. Discoveries such as the Altamura Skeleton, an almost complete ancient human skeleton found in Italy, have increased our understanding of exactly what they looked like. The upper jaw of a Neanderthal recently discovered in Spain revealed that Neanderthals used the gum of a poplar tree as sort of an ancient Aspirin when their stomachs hurt, and may have known about penicillin.