Biology Magazine

New Hominin Species Found: Australopithecus Deyiremeda Lived with Lucy

Posted on the 28 May 2015 by Reprieve @EvoAnth

The human family gets a new member as scientists have announced the discovery of a new hominin species. Australopithecus deyiremeda (meaning "close relative") was found in the Afar region of Ethiopia and dated via palaeomagnetic and radiometric techniques to between 3.3 - 3.5 million years ago. This puts itwithin the same timeframe and region as Lucy and her species Australopithecus afarensis.

Unfortunately, whilst we know a lot about Lucy and her kin the new Australopithecus deyiremeda fossils aren't that informative. They consist of an upper and lower jaw; along with several scattered teeth. However, these fragments were unusual enough to be labelled a unique species. It has thicker enamel and a larger jaw than earlier hominin species, but has more primitive teeth than later species. Compared to contemporary species - like Lucy - it has more forward placed cheekbones and smaller teeth. Nevertheless, it's overall similar enough to those other species to be join them as a member of the human family.

Getting a leg up on evolution

Whilst this jaw may be enough to label Australopithecus deyiremeda a new species it can't really tell us much more than that. A jaw isn't particularly handy for figuring out how a species walked or what it looked like. However, there may be a fossil which can shed some light on this: the Burtele foot. This mystery foot was found back in 2012 close to where Au. deyiremeda was later discovered. It's also the same age as this new species. Could this foot belong to Au. deyiremeda?

If it does then this raises some very interesting implications. This foot has some modern features (at least, modern by 3.3 million year old standards) that helped it walk upright, but also some more archaic ones for climbing trees. In other words, it looks like an evolutionary leftover. An older species that clung on as newer, shinier ones (like Lucy) evolved. Australopithecus sediba kind of falls in the same category.

If Australopithecus deyiremeda is the owner of the Burtele foot and another relic species it could provide invaluable information on what Lucy's ancestors were like. That period is something we don't know enough about. More data is always welcome.

That is, assuming more fossils are found. No pressure for the scientists then.

Australopithecus deyiremedahad lots of friends

The other notable aspect of this find is it confirms that our family was very diverse 3 million years ago. That was relatively early in our history. There was Australopithecus deyiremeda, Lucy and her species, and Keynathropus platyops, to name a few.

This early diversification looks a lot like adaptive radiation. When a species encounters a new opportunity or environment it can evolve quite rapidly into several different forms to fully exploit it. Darwin's finches are a great example of this, evolving a range of beaks in order to eat just about everything on the Galapagos.

If the human family underwent adaptive radiation this early it suggests we were doing something new and exciting. And we were doing it well. Our family was a success story before humans had even evolved!

Unfortunately all of these species do make life a bit more confusing when it comes to figuring out who was related to whom. And who made tools. And who owns certain feet. But at least that gives me plenty to write about here.

But is it legit?

Of course, all of this is assuming that Australopithecus deyiremeda is an actual new species. Since it's a member of the human family it shares many similarities with other known species; raising some doubts over this. The jaw is also one of the most variable parts of hominin anatomy.

That said, the teeth and jaw have enough unique quirks that I'm convinced it actually is a separate species (although I can see why some would be skeptical). Other fossils would be a really handy way for confirming this; as well as providing more information about the species itself.

So I guess we now play the waiting game to see what else these scientists can find. If you'd like to be brought any breaking news don't forget to follow EvoAnth. I'm always on top of it! Literally, this post is the first thing I did this morning.


Yohannes Haile-Selassie et al., 2015. New species from Ethiopia further expands Middle Pliocene hominin diversity. Nature 521:483-488

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