tag:blogger.com,1999:blog-4624586630299165335.post4142297162469828189..comments2024-03-14T09:50:44.315+00:00Comments on Psychological comments: Microcephalin makes a comebackAnonymoushttp://www.blogger.com/profile/09320614837348759094noreply@blogger.comBlogger8125tag:blogger.com,1999:blog-4624586630299165335.post-53311487652897144892014-06-01T00:57:05.226+01:002014-06-01T00:57:05.226+01:00Piffer's sixth author on that paper, Einstein....Piffer's sixth author on that paper, Einstein.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-34520760132511014772014-05-30T16:03:59.361+01:002014-05-30T16:03:59.361+01:00To say that the study is somehow deficient because...To say that the study is somehow deficient because it is 'correlational' is just plain statistically illiterate (this happens a lot unfortunately). Sure, correlation does not equal causation, but find me just one single instance of a causal relationship where there is no correlation (just one would suffice). At any rate, the study isn’t even correlational; it is explicitly mediational. Apparent associations between two variables can be mediated by other variables, which in turn cause the association (that includes yams and IQ by the way – try latitude, or temperature). The pattern of causal inference discussed in the paper is based on the direction of the effect of certain mediating variables (in this case infectious disease burden), as determined via multivariate analyses (most explicitly in the case of the Structural Equations Models on page 57). The robustness of this mediation is furthermore demonstrated via the replication of the same pattern of effects in two entirely different datasets. Granted, there is variance in the model which has not been accounted for, however given that the multivariate regressions pick up between 83 and 88% of the total variance in the criterion variables (hint: the relevant coefficients are listed next to R^2 in the tables) without falling afoul of serious multicollinearity, I am hard pressed to think what might have been missed by way of major mediators. If people are convinced by Just-Not-So stories of geography, founder effects, hunter-gatherers or other factors in generating the observed pattern of mediation then I invite them to put these to the test and prove me wrong (all data are appended to the publication making this a potentially very simple task for anyone with a half-way decent stats-package). Kutner et al. (2005) is an excellent place to begin learning about applied linear modelling incidentally.<br /><br />Reference<br /><br />Kutner, M., Nachtsheim, C., Neter, J., & Li, W. (2005). Applied linear statistical models (5th ed.). Irwin, California: McGraw-Hill. <br /> Michael A. Woodleynoreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-26260734493281344422014-05-28T18:22:15.660+01:002014-05-28T18:22:15.660+01:00Right, but when the same pattern occurs for 14 IQ ...Right, but when the same pattern occurs for 14 IQ increasing or 56 height increasing alleles (as shown by Piffer), arguing for random drift becomes really silly.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-83886534933740907262014-05-28T17:27:51.526+01:002014-05-28T17:27:51.526+01:00I think that the problem of false positive certain...I think that the problem of false positive certainly bedevils any search for individual genes related to intelligence, and to group differences in intelligence. Anonymoushttps://www.blogger.com/profile/09320614837348759094noreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-25605810853962610822014-05-28T16:40:29.555+01:002014-05-28T16:40:29.555+01:00Peter Frost commented on that paper, and I happen ...Peter Frost <a href="http://evoandproud.blogspot.com/2014/04/the-riddle-of-microcephalin.html" rel="nofollow">commented on that paper</a>, and I happen to agree:<br /><br /><i>"I have mixed feelings about this study. Looking at the world distribution of this allele (see above map), I can see right away a much higher prevalence in Eurasia and the Americas than in sub-Saharan Africa. That kind of geographic distribution would inevitably correlate with IQ. And it would also correlate with the prevalence of infectious diseases.<br /><br />Unfortunately, such correlations can be spurious. There are all kinds of differences between sub-Saharan Africa and the rest of the world. One could show, for instance, that per capita consumption of yams correlates inversely with IQ. But yams don't make you stupid.<br /><br />More seriously, one could attribute the geographic range of this allele to a founder effect that occurred when modern humans began to spread out of Africa to other continents. In that case, it could be junk DNA with no adaptive value at all. There is of course a bit of a margin between its estimated time of origin (circa 37,000 BP) and the Out of Africa event (circa 50,000 BP), but that difference could be put down to errors in estimating either date."</i><br /><br />Not that either he or I think there's nothing to this, but this could be well, correlational, with the cause of the association operating quite a few links away.<br />JayManhttp://jaymans.wordpress.com/noreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-90352578223724573862014-05-28T15:11:21.696+01:002014-05-28T15:11:21.696+01:00That's just an abstract copied and pasted from...That's just an abstract copied and pasted from LCI conference proceedings, with no input from you.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-56051396464120772852014-05-28T14:31:53.625+01:002014-05-28T14:31:53.625+01:00Piffer not forgotten, just not mentioned in that p...Piffer not forgotten, just not mentioned in that post, but in this one http://drjamesthompson.blogspot.co.uk/2014/05/lci14-davide-piffer-human-polygenic.htmlAnonymoushttps://www.blogger.com/profile/09320614837348759094noreply@blogger.comtag:blogger.com,1999:blog-4624586630299165335.post-3151742196510640772014-05-25T11:05:37.525+01:002014-05-25T11:05:37.525+01:00Fair enough. This is sound indirect evidence for a...Fair enough. This is sound indirect evidence for an evolutionary link between a gene and population level intelligence. However, you seem to be forgetful of the DIRECT evidence provided by Piffer in his 2013 Mankind Quarterly paper, followed by two papers published on Open Behavioral Genetics (http://openpsych.net/OBG/) which found clustering of 12 IQ increasing alleles across populations and strong correlation (0.9) with country IQ.Anonymousnoreply@blogger.com