Nathan Clark writes:
Thanks for featuring our study on PON1! I enjoyed the episode. I can answer a few of the questions that came up about this interesting enzyme. For starters, PON1 has been extensively studied in humans as well, and we generally have strong protective activity against chlorpyrifos and diazinon. Like you suggested, there are human alleles with differing activities, and so certain individuals are more susceptible. Interestingly, those same alleles are also associated with risk for atherosclerosis. Next, yes, the high dN/dS ratios in the bats and primates are intriguing to us, but we haven’t been able to pin the reason down yet. Any ideas that you or your listeners have would be helpful! I hope all is well in Utah and New York.
Vincent and Nels,
In TWiEVO Episode 34, you had a short discussion and some questions about marine animals’ sense of smell.
It helps to think about this if you back up one level to see smell as one form of chemo-sensitivity. This groups smell and taste together.
From that perspective in an evolutionary context, smell in land animals probably emerged as taste sensors adapted for use in air.
Also note that fishes have nostrils. (Check out sharks pictures!)
Nostrils on either side of the face “taste” slight differences in the environment, enabling mental mapping of scent/taste sources, be it “fish or fowl.” (Dogs are noted for their “stereo” sense of smell.)
So as marine animals evolved to live on land, they arrived with nostrils, and apparently responded to evolutionary selection pressures that favored nostrils with chemo-sensitivity to airborne chemicals. (The nose still maintains a damp environment to get the job done.)
I’ve read that our experience of flavors depends more on our nostrils than our tongue.
I get the impression that selection pressures favored mouths that could make quick, broad assessments of whether what we’re about to swallow is safe (sweet / umami), needed right now (salt), or potentially dangerous (bitter).
Our noses, meanwhile, provide a more nuanced assessment of exactly what we’re eating or are walking through.
A final digression:
Sensing and responding to the varying chemicals in one’s surroundings is a trick that seems to be essential to all biological entities at all scales.
One might, though, push this too far. Do cellular viral defenses “smell” the presence of viruses? Does DNA replication depend on “tasting” start and stop codons? Is quorum sensing based on the smell of the crowd?
Probably not the best terminology.
As always, I thoroughly enjoyed this episode of TWiEVO. I especially appreciate Nels’s ability to explain the more arcane aspects of evolution with readily understood analogies.
Finally, a rant:
I urge everyone listening to this podcast who hasn’t yet done so, immediately set up a monthly donation to TWiV.
You probably don’t think twice about adding a $1.00 candy bar or $1.50 soft drink to your weekly or bi-weekly grocery shopping cart.
Do the world (and your health) a favor and set up an automatic Patreon contribution of that money.
And when you’re standing in the checkout line, remind yourself that you have already used that money to do something good for many, and not do something bad for yourself.
[Vincent: Feel free to read this rant on all the other podcasts.]
Looking forward to future TWiVs.
— Tom in Austin
Hello Vincent and Nels,
This is Ornob from Bangladesh. I will start by thanking you once again for this lovely podcast that I look forward to every month. The recent episodes on neutral theory and convergent gene loss in marine mammals gave me a lot to think about.
I don’t know if this is entirely appropriate, but since you guys must peruse the wide field of evolutionary biology to pick out gems for the podcast, I wanted to ask you about researchers who are doing great work along the lines of Harmit Malik, Sara Sawyer, and Nels himself, as well as the Neandertal paper from Luis Barreiro’s lab you guys did. Basically labs that study the evolution of some aspect of immunity or host-pathogen conflict, and heavily use computational approaches to drive experimental strategies. I am researching labs to figure out what departments to apply to for a PhD, and would really appreciate your insight to make sure I am not missing out on some great line of work! Apologies if the query is a little too broad.
Tarzan and the Lion Man
Edgar Rice Burroughs
“‘I had always been intrigued by Lamarck’s investigations and later by Darwin’s. They were on the right track, but they did not go far enough; then, shortly after my graduation, I was traveling in Austria when I met a priest at Brunn who was working along lines similar to mine. His name was Mendel. We exchanged ideas. He was the only man in the world who could appreciate me, but he could not go all the way with me. I got some help from him; but, doubtless, he got more from me; though I never heard anything more about him before I left England.
“‘I determined that heredity could be controlled through the transference of these genes from one individual to another. I learned that the genes never die; they are absolutely indestructible—the basis of all life on earth, the promise of immortality throughout all eternity.
# # #
Might reading this have been the inspiration for crafting the fiction into fact?
“World’s simplest animal reveals hidden diversity”
Dear Team TWiEVO,
I had a quick listener pick. For those who haven’t stumbled onto this book, it is a fantastic classic.
The book is On Growth and Form, by D’Arcy Wentworth Thompson. The version I own is abridged and edited by John Tyler Bonner… and yes that is the same John Tyler Bonner of slime mold fame.
Keep up the great work, and don’t shy away from the weird stuff.