Homo naledi, our newly discovered evolutionary cousin

[RainDreamer]

Scientific journal source:

http://elifesciences.org/content/4/e09560.full

News source:

http://voices.nationalgeographic.com/2015/09/10/homo-naledi-1500-fossils-cave-revolutionize-human-evolution-family-tree/

http://www.techinsider.io/new-human-ancestor-homo-naledi-hominin-discovered-2015-9

Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.

They seems to be representing an evolutionary bridge between our ape form and our human form. More fossils are still being uncovered, but this seems very interesting already.

Edited September 10, 2015 by RainDreamer
fixed title

[Kerbart]

Some caution is required; this wouldn't be the first time it was claimed "the missing link" was found. At the same time it would be exciting to see this void in the evolution of mankind filled.

[RainDreamer]

Some caution is required; this wouldn't be the first time it was claimed "the missing link" was found. At the same time it would be exciting to see this void in the evolution of mankind filled.

The scientists deliberately tried to avoid calling this species "the missing link", and call them more like a bridge. They haven't been able to date the bones properly yet, and it could very well be much younger than they thought, making them an off shoot of evolution that somehow survived for a long time rather than a direct link between us and our ancestors.

It is all up in the air right now till they figure things out. But the exciting thing is that we found more stuff related to our evolution.

[AngelLestat]

A missing link can be called when you need a bit more of evidence to relate some species with other in a timeframe.

But this was used for religion as an excuse to reject evolution, which is funny, because we already found hundreds of "misssing links".

you may have bones from 5 millions hominid, then bones from 1 millions back homind, after some time you find a 4 millions back homind, then a 3 millions back homind, then a 3.5 millions back homind ("the missing link" between 4 and 3), and then the process continues.

Is not even sure where we can called a different species or not, because we dont know if the 4 billions "specimen found" would be able to procreate a not sterile child" with a 3 billion specimen found.

So they may still count as the same species.

We were able to procreate with the neanderthals after all.

Edited September 10, 2015 by AngelLestat

[tater]

One, for the thread title, it's Homo naledi, the species is never capitalized, just the genus.

Two, "missing link" is not really a thing. Evolution is not that linear. A bette model might be more akin to electron density distributions. Think of branches as being sort of fuzzy, it's not like one individual looks like Homo erectus, and his offspring looks like archaic Homo sapiens. It's fuzzy (though a specific feature that makes the clade branch would obviously change for the different species attribution, and for paleo stuff, that means bone morphology). Cool stuff, though!

Edited September 10, 2015 by tater

[0111narwhalz]

More than anything else, evolution is like dust settling upon a shelf. For a while there's no perceptable change, but in the end, you glance over and realise, "Huh. That shelf is dusty." How many specks of dust per area make a not-dusty shelf, dusty? Furthering the analogy, some specks are bigger than others, just as some mutations are bigger than others.

[monstah]

I read an article on that yesterday, and found it very interesting. No sensationalism, no "missing link" terminology. They can be very certain it's a new species because "at least 15 individuals were found, almost every single bone in the body found multiple times". That's data right there!

[lajoswinkler]

The idea for a "missing link" is mute just like "chicken or egg" question is. People who propose such ideas simply don't know how evolution works. Mostly journalists and crackpots.

This is simply one of our cousins.

[PB666]

Some caution is required; this wouldn't be the first time it was claimed "the missing link" was found. At the same time it would be exciting to see this void in the evolution of mankind filled.

The problem is that the find does not have a reliable geological date. You are correct, because if this is from the 1.8 to 1.9 mya range or later, then there are comparable finds in the Caucasus region, homo erectus georgicus, that are similarly a small brain on a otherwise generically human morphology brain morpholgy was variable. And also we have that small, medial australopiticine/erectine skull morphology of Homo floreinsis that dates to 13 kya. If this thing dates to 3 mya then its a very important find, even 2.5 mya is important, it basically blows all of paraantrops out as human contenders and only leaves the oldest australopithicines as contenders. So the dating is important.

The real problem in pre-erectine studies has been homo habilis and the smattering of habiline remains that have been discovered. Early studies placed these as tree dwellers, because of upper body strenth, but also indicated they would have been poor hunters, as time went on a pot of variable traits were added that confused the issue. The problem has been that the finds are largely fragmented and fractional. These naledi finds are mostly complete and suggest communites with lots of variation, not dissimilar to what was seen with the Georgian erectines. They were definitely biped, and probably obligate bipeds, which would make habilis an irrelvant catagorization if these were contemporary. Given the distance to the caucasus, and proximal variation in the cave I don't think a contemporary with the georgian find constitues a new species.

I should point out that morphological variation tapers in Africa slowly while OoA humans radiated from Africa, and its likely that the rise of agriculture and cultivation put and end to structural variation in many areas. Thus maybe we are a bit biased by recent selection in the modern era, Erectus as a species maybe older than we think. Interestingly this find has made surprisingly little noise in the anthro discussion boards so I wonder if people have already discounted this as another early homo data point. While it is possibile that two hominid species lived in africa until late, Tishkoffs recent studies in africa and the recent discovery of an offset Y chromosomal PMRCA make this scenario only possible if one of the species lived in extreme North Africa, IOW the pre LGM variation we see in SSA is probably human, so the collapse of morpholgy post dates the genetic constriction that occurred in the human population.

What this all says, basically is that variation is a longlasting trait of pre agrarian humans, and that we should not be so quick to call new species unless those variants are really diiferent and show strong regional identities. So yeah, its prolly a part of the missing link, but not the only one out there. Our ancestors were mobile, they did not stay in one place, and popsize estimates based on DNA suggests that we were spread thinly before OoA. In that context, this makes more sense.