Comments on: Seasons of Life http://www.peterdsmith.com/archives/2009/08/11/seasons-of-life/ Kafka’s mouse Thu, 01 Jul 2010 01:49:28 -0700 hourly 1 http://wordpress.org/?v=3.0 By: Michael Gross http://www.peterdsmith.com/archives/2009/08/11/seasons-of-life/comment-page-1/#comment-850 Michael Gross Tue, 18 Aug 2009 08:46:26 +0000 http://www.peterdsmith.com/?p=575#comment-850 ok, thanks ! I guess more research is needed on that one. for instance comparisons between people of European origin and Africans whose ancestors may never have moved outside the tropics. ok, thanks ! I guess more research is needed on that one. for instance comparisons between people of European origin and Africans whose ancestors may never have moved outside the tropics.

]]> By: PD Smith http://www.peterdsmith.com/archives/2009/08/11/seasons-of-life/comment-page-1/#comment-848 PD Smith Mon, 17 Aug 2009 11:52:37 +0000 http://www.peterdsmith.com/?p=575#comment-848 I think the authors would place the emphasis on the adaptations of our early ancestors that enabled them to survive & reproduce by anticipating seasonal changes. These, they say, "still reside deep within our metabolism and life histories". The authors suggest that as early humans moved from the equatorial regions to higher latitudes the ability to adapt to seasonal change became a factor in their survival: the battle with the seasons became an engine of natural selection. They admit that the question as to whether there is an innate circannual rhythm in humans or whether it is learnt behaviour is "arguable". However, given the amount of evidence they present regarding seasonal effects in human health etc, the implication is that this is an innate mechanism which has yet to be fully described. It's an interesting book - well worth reading. I think the authors would place the emphasis on the adaptations of our early ancestors that enabled them to survive & reproduce by anticipating seasonal changes. These, they say, "still reside deep within our metabolism and life histories".

The authors suggest that as early humans moved from the equatorial regions to higher latitudes the ability to adapt to seasonal change became a factor in their survival: the battle with the seasons became an engine of natural selection. They admit that the question as to whether there is an innate circannual rhythm in humans or whether it is learnt behaviour is "arguable".

However, given the amount of evidence they present regarding seasonal effects in human health etc, the implication is that this is an innate mechanism which has yet to be fully described.

It's an interesting book - well worth reading.

]]> By: Michael Gross http://www.peterdsmith.com/archives/2009/08/11/seasons-of-life/comment-page-1/#comment-847 Michael Gross Mon, 17 Aug 2009 10:08:56 +0000 http://www.peterdsmith.com/?p=575#comment-847 intriguing stuff. I vaguely know how circadian clock works and the annual timing in plants. With Homo sapiens there is a problem -- as we evolved in tropical Africa without any daylength variations, we can't have evolved a circannual clock. We can of course respond to variation of day length that we experience now (as we do in SAD), but I would find it difficult to rationalise how we would have evolved a season clock in the absence of seasons (defining "clock" as something that runs on even if the external cues are switched off, as the circadian clock does if you live in permanent light or darkness). Do the authors have an answer to this ? intriguing stuff. I vaguely know how circadian clock works and the annual timing in plants. With Homo sapiens there is a problem -- as we evolved in tropical Africa without any daylength variations, we can't have evolved a circannual clock. We can of course respond to variation of day length that we experience now (as we do in SAD), but I would find it difficult to rationalise how we would have evolved a season clock in the absence of seasons (defining "clock" as something that runs on even if the external cues are switched off, as the circadian clock does if you live in permanent light or darkness). Do the authors have an answer to this ?

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