a bonobo humanity?

I’ve long had an interest in bonobos, and now I read [via 3QD] that they’ve had their DNA sequenced, and researchers are trying to find clues in their genome as to their relatively placid and highly sexual behaviours. So we can now compare what the sequencing tells us with what has been learned in the field.

I’ve dealt a little with bonobos before in one of my experiments with podcasting here, where I told the story of how they were separated from chimps physically by the Congo River, maybe a couple of million years ago. The sequencing shows that this separation was radical and permanent, with modern bonobos showing no closer genetic affinity with their chimp neighbours across the river than with chimp populations much further away. It looks like it’s going to take some time, though, to identify in genetic terms the particular changes that have occurred since the split. In fact, it appears easier to identify environmental factors to explain bonobos’ more relaxed and non-aggressive behaviour when compared to chimps. North of the river the chimps compete for territory and food with gorillas, whereas south of the river the bonobos face relatively little competition.

The sequencing of one particular, possibly ‘atypical’ bonobo doesn’t necessarily provide all the answers, any more than it does with humans or any other species. In this case the specimen was an 18-year-old-female, Ulindi, who displayed quite a bit of aggression to one of the research team. In any case, there’s a lot of variation in bonobo behaviour, and to pick out one individual as ‘typical’ for sampling is as questionable as assuming that any one human is typical. The bonobo is the last of the ‘great apes’ to have its genome sequenced, following the chimp, the gorilla and the orang-outang, but some if not all of these species have sub-species, and there’s enough genetic variation within species to make it vital that we sequence more than one, and even more than a few, individuals of each species. As it is, preliminary findings from Ulindi’s genome indicate that we have a long way to go:

As a start, Prüfer’s team identified regions of the bonobo genome that differ from those of chimps and that may have evolved in bonobos since the split. Many of these regions contain no genes, while the genomic region that seems to have evolved the fastest in bonobos encodes a microRNA molecule that probably regulates the activity of as-yet unidentified genes.

So the story is complex and will take time and a lot more research to tease out. Some 1.6% of our genome is more closely related to that of bonobos than to that of chimps. The significance of this connection will also take time to establish. Mapping our genome to our closest relatives in this way will help us to determine how exactly we are different, to home in on that subsection of our genome that is unique to us. We’re still not clear on that, and then we have to try to work out what emerges from that subsection, in terms of physiology, behaviour and so forth.