&quot;We don&#x27;t know if Neanderthals count as humans, or if chimps do, because we can&#x27;t agree on the defining features of a human&quot;<p>I don&#x27;t think any scientist disagrees that chimps aren&#x27;t humans. The issue in question here is how far back in our lineage do humans go, vs. some other species.<p>Given that evolution happens continuously, and not in a discreet way, it is completely impossible to objectively determine precisely when we &quot;became&quot; humans, something which is exacerbated by the fact that we&#x27;re only looking at fossils.<p>Perhaps, like porn, we should not try to define it further, but there&#x27;s no question that, when looking at today&#x27;s existing species, you know a human when you see &quot;it&quot;.