Please explain how the date was arrived at. “400,000-year-old dental tartar” —exactly, to the year? Lastly, how do they know it was tartar? Did they have teeth back then that accumulated tartar through a diet the same as our modern diet? What was the diet? What thing did these teeth with “tartar” belong to? Human, animal, and how was that determined?
Crack a book, troll.
I suspect that 400,000 was meant as “around,” not “exactly” that time period. If you read the article which you can click to where it says Read more ....., then you will have most of your questions answered. Paleontologists are thoroughly trained to differentiate teeth from various animals and species of hominids. If you are really curious you could Google the names of the authors or researchers and find where they have published. Then you could go to a library or Google the published article and get the minute details.