Evolution 2011: hot research—with cats!

June 19, 2011 • 12:18 pm

I am not a big fan of Twitter, though the WEIT posts go out on it.  I hate the word “tweet,” which rankles as much as “blog,” and constant personal “tweeting” seems to me more than a tad solipsistic. But how could I not post this “tweet” from the Evolution 2011 meeting feed (#evol11):

RT @surt_lab factoid from #evol11 geographic distribution of lactose tolerance in cats parallels that in humans < would ya look @ that!

If you’ve read WEIT, you’ll know that those human populations with a history of “pastoralism” (raising cows, sheep and goats for milk) have a high frequency of genes for lactose tolerance compared to those human populations that don’t consume much milk.  Further, the allele for lactose tolerance increased in frequency only in the last 10,000 years, which parallels the time when pastoralism began. (The gene, by the way, is one that allows the enzyme lactase, which breaks down lactose into sugars, to keep being expressed into adulthood. That gene is usually turned off after childhood, when, historically, people no longer nursed.)

It’s a really good example not only of evolution in “real” (or semi-real) time, but also of gene/culture coevolution: a change in human culture—the domestication of milk-yielding mammals—has created a “natural” selective pressure that changed our genes.  This, of course, is due to the tremendous reproductive advantage of having access to such a rich food source, which you can gain only if you can digest it.  (The reproductive advantage of digesting milk in a pastoral population is a whopping 10%!).  You can read more about this system at the Understanding Evolution site.

Apparently, the same genetic changes have occurred in cats commensal with humans.  Clearly, cats have been fed milk by their pastoral owners for a considerable amount of time: cats appear to have been domesticated between 8,000 and 5,000 years ago.

Self aggrandizing note: Allen Orr and I have co-signed several copies of our book, Speciation, on sale at the Sinauer booth at these meetings.  Jointly signed copies are rare—Orr and I are rarely at the same place at the same time—so pick up one of these rarities now. (Note: there is no surcharge!)

20 thoughts on “Evolution 2011: hot research—with cats!

  1. In reaction to the ‘Self aggrandizing note’ (and my 2 reasons for not going after a doubly-signed copy 😉 ):
    I realize from the reviews at Amazon that ‘Speciation’ isn’t a book for lay people like myself.
    I wonder if THAT is a factor in it being about SIX times as expensive as WEIT?

    1. Yes, let me emphasize that the book is aimed at evolutionary biologists: students, postdocs, and professors. I have told my non-biologist friends, even those who like Dawkins and Gould, not to buy it, because it’s pitched at a fairly high technical level.

  2. Well I brought my copy of WEIT along. Not sure yet when I will be in Chicago so I will go fanboi on you and get it signed after your lecture. Did the same to Ken Miller yesterday. Ha!

  3. I believe the new terminology is “Lactose Extension”. That is, we are all lactose imbibers at ages 0-6 (max range) but then something switches off in some people, and they can no longer digest milk. A single gene, if you possess it, allows you to digest milk indefinitely. That is, the expiration is “extended”.

    1. Wasn’t this called “Lactase persistence”?
      My idea goes as follows: Normally, Lactase synthesis in mammals stops if they are old enough to drink beer, so their younger siblings get enough milk (that should be enough to save two or more young siblings, so even fatal starvation of the old one would pay off). I’d like to know how the SNPs found by Tishkoff work: Are they just broken binding sites for downregulating TFs?

      1. Sorry, I can’t help it…. what does the Scottish National Party have to do with this, and how was Tishkoff able to find them?

      1. I don’t know why, but Google says it’s common & *usually* it’s not a problem, but all statements in the human medical arena DO need the modifier *usually* because some conditions/diseases can cause the change, eg IBS which ain’t no joke to have I believe

        Search terms:
        primary adult onset lactase deficiency
        secondary adult onset lactase deficiency

        Produced loads of results such as:

        Actually it’s adult lactose tolerance for cows’ milk that is unusual 🙂 See Lactose Intolerance is Normal!

        & Here QUOTE:

        …adult loss of lactase is a normal mammalian trait […] adult ability to split lactose is an “abnormal” evolutionary innovation

  4. “hot research — with cats!”

    I’m getting the distinct impression that this post is purely to annoy and provoke PZ Myers.
    He’s probably already working on a counter attack in this recent flare-up of the cephalopod – felid [octopussy] wars.

  5. I have a vague idea that we have a system similar or identical to the lac operon. Is this just my faulty memory at work?

  6. Milk facts (or urban myths ?)that I’ve ‘known’ for years. Are they true ?:

    ** In TV ads for breakfast cereals, the ‘milk’ they use is actually white paint + a touch of thinner (turpentine or similar). It looks thicker & films as more real than actual milk

    ** To people who can’t tolerate milk products the milk/cheese/yoghurt/kefir consuming portion of the human race give off an acrid sour milk odour

    I’m intrigued by Camel Milk USA

    I’m off for a lie down now

  7. How extremely interesting! That explains why my aunt’s cat could not drink milk *at all* (drink milk– spray the wall with diarrhea). Clio can’t handle much, either, come to think of it. A little yoghurt is ok for her, though, as it is for many lactose intolerant people.

    As a side note– a large number of people (like my dad) who think they’re lactose intolerant are really reacting to excessive amounts of whey used as a filler ingredient in processed foods. My dad’s lactose tolerance returned somewhat when he quit eating anything with “whey” in the ingredients list, which turns out to be practically everything. He still uses treated milk, but can have real cheese (*not* processed cheese slices!). Moral of story: eat real food.

    1. Q: Do gluten intolerant people have a remnant of pre-agriculture genes or is the intolerance the result of newer mutations?

  8. Does anyone know if it’s the same for dogs too? My guess is that it would be but some evidence would be handy.

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