[ExI] darwin again: ants masturbate aphids... was RE: New Enlightenment talk

[spike]

> http://www.heise.de/tp/r4/artikel/6/6143/1.html
> Max

Thanks Max.  There was something in your pitch that really caught my
attention, about Darwin being influenced by economic theory.  I am reading
Origin of Species for the first time, although Darwin has been a hero to me
since a long time ago.  I am astounded at how good he was, and how carefully
he observed nature.  I have posted here about watching ants interact with
aphids on my fruit trees.  Darwin wrote something in Origin that blew my
mind.  He was puzzling over why aphids would give nectar to the ants.  The
usual explanation is that they do so in exchange for protection against
aphid-devouring lady bugs, but that explanation has some difficulties that I
noticed last summer.  The ants take the nectar, but they do not devour it on
the spot.  Rather they take it down under ground to their sisters.  If their
path is blocked, they wander around in the tree for days, with the nectar,
eventually falling or leaping from the tree.  The aphids eventually go away
too, but there seem to be far too few lady bugs to account for the missing
aphids.  The aphids appear to have gone off searching for ants to give away
their nectar.

Darwin commented in Origin that the ants stroke the aphids with their
antennae in such a way that they then excrete the nectar that was previously
apparently within the body of the aphid.  He claims the ants do devour the
nectar, so I need to observe again to witness that phenomenon.  He describes
trying to simulate the ant's actions on the aphid by stroking the aphid with
a hair, but the aphid apparently wasn't fooled by the enormous heretic and
did not excrete the nectar.

So there you have it.  Ants masturbate aphids, the little harlots.
Biologists just don't have the touch.

Origin of Species is a terrific book.

spike