Evaluating the Neanderthal theory with 23andme

23andme, a company that sells genetic tests to individuals, has developped a Neanderthal heritage estimator: http://spittoon.23andme.com/2011/12/15/find-your-inner-neanderthal/. This estimator uses factor analysis on all the single nucleotide polymorphisms (SNPs, currently almost 1 million) that are part of their genetic test. This means we would expect the estimator to give a good indication of the SNPs that were introduced from Neanderthal after they met modern humans some 30,000 to 40,000 years ago. They use native Africans as a control group, so any SNPs that have spread to the whole world would be discarded. Any SNPs that were introduced earlier would also be discarded.

So how does this estimator correlate to neurodiversity (Aspie) score in Aspie Quiz? We would expect a large correlation if recently introduced SNPs from Neanderthal could explain most of today’s human diversity, but this is not the case. With a material of 167 people of European descent (out of totally 94,000) that did both Aspie Quiz and 23andme, there is a correlation of 0.12. That means that p < 0.07 that there is no relation between 23andme Neanderthal heritage percentage and Aspie Quiz scores (and that there is 93% probability that they are related).

So it does seem like 23andme Neanderthal heritage estimator does support the Neanderthal theory, but the correlation is much smaller than what we would expect. There could be many reasons for this low correlation, but the major reason is probably that science has not found any single SNP that could explain more than 1% of ASD. Since ASDs have no large relation to SNPs, we would not expect it to have a large correlation to any SNP-based genetic data. The largest genetic correlation is with Copy Number Variation (CNVs), but the Neanderthal genome does not include CNVs, and is composed of many small fragments that could prove hard to analyse in the context of CNVs.

Some further break-down of the data reveal other interesting insights. It seems like some questions in Aspie Quiz have larger correlation to 23andme than others. It is especially notable that questions related to Neurotypical compulsions and Aspie hunting seem to have considerably higher correlations to 23andme than others. These issues are atypical in the analysis of Aspie Quiz since they have too low diversity in relation to the number of different issues they cover. They seem to be recent evolution in modern humans (Neurotypical compulsion) and Neanderthal (Aspie hunting). This can explain why the correlation is lower than expected. What the 23andme estimator calculate is recent evolution in modern humans and Neanderthal, but most of the diversity in Aspie Quiz is much older than the 250,000 years that Neanderthal existed. In fact, Aspie Quiz suggests that neurodiversity is close to 2 million years old, meaning that only 10-15% of neurodiversity would be anticipated to have evolved in Neanderthal, while the other traits evolved in their ancestors in Eurasia.

But why then do 23andme mainly detect recent human evolution, and not the more ancient evolution of neurodiversity in Eurasia? Most likely because some of this diversity has spread one way or another back to Africa during the last two million years, and when the SNPs already exist in some (possibly low) proportion among Africans, 23andme would discard them as not of Neanderthal origin.


2 Responses to “Evaluating the Neanderthal theory with 23andme

  • Do any pre-evolved humans still exist?
    April 29th, 2012 12:03

    […] […]

  • schoolresearch
    July 8th, 2012 00:02

    Hey Leif Ekblad,

    For school I’ve assignment of autism/asperger (i’ve chosen to talk about autism/asperger)

    I introduce myself.
    I’m diagnosed myself with Asperger Syndrome and Dyslexia.
    I’m from belgium, so my english is not perfect.

    Both ‘disorders’ in my opinion are variation in genes and not something to be diagnosed I think. I’ve read many posts on forums and your neanderthaler theory. Maybe the neanderthaler theory is incorrect however, you’ve studied alot of the aspie behaviour.
    And I’m interested in information of aspies about empathy (without subjectivity, not neurotypical empathy), behaviour and so on, viewed with objectivity, not subjectivity.

    I became inspired by you when you said: I’m married with someone with asperger and I can empathise very good with her.

    I personally met an asperger female on school and like you said I could very easy relate to her, we have enormous empathy for each other.
    So I think the bad fit of neurotypical and aspie can have this bad emapthy in both direction as an effect.
    However, neurotypicals are more dominant (because they are the majority). This is the reason I think we have ‘a lack of emapthy’.

    I also read about your evolutionary psychology theorie in aspie-aspie relationships and it fits me very well.
    We always stare to each other in class and we stay close to each other for maybe a year now?
    It is maybe an adaptation in aspies.

    Thank you,
    I hope you respond!

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