Saturday, April 10, 2010

Facebook Foolery

Yesterday a Facebook friend of mine posted a status update that got me thinking. I haven't asked his/her permission to reproduce it here, so I won't mention names unless that person decides to identify themselves in the comments.

The Status update was as follows:

"Scientists have discovered yet another link their evolutionary chain: a couple of supposedly several-million-years-old skeletons of "humanoids" that resemble orangutans. Has it occurred to any of those brilliant scholars that those really ARE orangutans?? Hello?"

Without going into too much detail, this person is intelligent, creative, well educated and has an interest in the sciences. How, then, could someone like that be so completely wrong in every detail?

Before I delve into that question, let's first look at why it's wrong.

Given the timing of the post, I'm assuming that it refers to the recently announced discovery of two skeletons belonging to what is being called Australopithicus Sediba - a supposedly previously undiscovered hominid species native to the area surrounding Johannesburg, South Africa (my home - one of the reasons I'm particularly interested in it).

Australopithicus Sediba

As with any proposed new species, particularly those that are claimed to be part of the human ancestral line, there's a considerable scientific controversy about it. This is a normal part of the scientific process: whenever a new discovery is made and a claim put forward as to its place in the scheme of things, it falls on those discoverers to defend their argument from the scrutiny it will receive from the rest of the scientific community. If they're successful in doing so, their new idea will eventually become part of the scientific consensus.

Questions usually raised in cases like this are things like "Is this really a new species?", "Is it really as old as it seems to be?", "Does it really represent a species that is ancestral to Homo Sapiens, or is it only a cousin?" and so on. You may recall the back and forth we've seen over the discovery of "Homo Floresiensis" several years ago. The questions in that debate haven't yet been finally settled, and it may be several more years before they are. The same will likely be true of Australopithicus Sediba as well. John Hawks has written an excellent overview of the controversy surrounding it.

Okay, so that's the background, let's look at the actual claims in the status update:

"Scientists have discovered yet another link their evolutionary chain"

Describing the taxonomical classification of various species as a "chain" shows a pretty clear misunderstanding of how evolution works, and particularly the notion of common descent. For this reason, scientists almost never describe it as such anymore, and seldom, if ever, use the term "missing link" to describe new species either. Simply because those analogies aren't very useful or descriptive. You're far more likely to hear scientists referring to "branches" or "twigs" on the "Tree of life", because that imagery more closely resembles the actual structure of phylogeny. That doesn't stop tabloid newspapers from using the term "missing link" at every available opportunity... but if we haven't learned by now not to trust the mainstream and tabloid media for science news, we are truly lost.

Tree of Life

"...a couple of supposedly several-million-years-old..."

"Several" is an interesting choice of words here. The paper clearly states that the skeletons are less than 2 million years old - between 1.78 and 1.95 million, to be precise. That's not to say that those dates are subject to possible revision, but nobody is claiming right now that they're any older than that. Why implicitly inflate the age?

"...skeletons of "humanoids"..."

The correct term here is "hominid". "Humanoid" is a term used in science fiction to describe species closely resembling humans, but who don't necessarily have any biological relation to us. "Hominid" is a term used in paleoanthropology to describe a subset of ape species that are human-like, including Homo Sapiens - us.

"...that resemble orangutans..."

This is an even stranger choice of words. Why orangutan? Why not gorilla or chimpanzee?

Let's look at a little background in ape phylogeny. Today there are two subfamilies under the family of the "Great Apes" (Hominidae): Pongo (orangutans) and Homininae (gorillas, chimpanzees and humans). That means we're all pretty closely related. But it doesn't mean we're equally closely related to each other. The common ancestor between the Pongo subfamily and the Homininae subfamily lived a lot longer ago than the various common ancestors of the different species within the Homininae subfamily. That means orangutans are our most distant relatives within this family.

Ape Phylogeny

The subfamily Homininae is itself divided into two tribes: Gorillini (gorillas) and Hominini (chimpanzees and humans). That means that within that subfamily, gorillas are our most distant ancestor.

In turn, the tribe Hominini is divided into two subtribes: Panina (common chimpanzees and bonobos) and Hominina (all the different species of humans). Whether or not Australopithecus Sediba is indeed a new species, there is no doubt that it does fall within the Hominina subtribe, which makes it a human species. Which means that it most closely resembles other human species. It less closely resembles chimpanzees. And even less closely resembles gorillas. And even less closely resembles orangutans.

So why choose orangutans to compare it to? I don't get it.

"Has it occurred to any of those brilliant scholars..."

A scholar is a specialist in the humanities: art, history, philosophy. These people are not scholars, they are scientists. Describing a scientist as a 'scholar' is a subtle way of undermining their credibility.

"...that those really ARE orangutans?"

Although I can't read the minds of the scientists involved, I'm pretty certain that this thought has occurred to them. In fact, it's not necessary to be a scientist to make that determination, we can all do it right here together.

Here is the skeleton of Australopithicus Sediba:

The Malapa Skeletons

Here is a skeleton of an orangutan:


They certainly bear a striking resemblance - as do the skeletons of all the great apes. But they are clearly not the same. Even an untrained eye can see the clear differences between them.

Which brings me back to my original question: why would someone say something like this?

I suspect the answer is twofold:

First, the person is very religious (probably a Young-Earth Creationist) and therefore has a vested ideological interest in refuting the claims of paleoanthropologists.

Second, given that, I'm guessing the person relies on a combination of mainstream media (which is incompetent) and Christian publications (which have the same ideological bias, and are also incompetent) for their information.

I think it's pretty sad, really. A combination of selection and confirmation biases have conspired to make this person make a fool of themselves on the Internet. Unfortunately it's not the first time this has happened to someone, and it won't be the last.