How the squashes hitched a ride with humans

Squashes are funny, as fruits go. Even after years of selection for human consumption they have thick, hard rinds, they’re not particularly sweet — in fact, they contain bitter compounds called cucurbitacins — and their seeds don’t separate from their flesh very easily. That all suggests that the wild ancestors of butternuts and pumpkins were dispersed by large mammals, but squashes are native to the Americas, and there haven’t been many large mammals of the sort that would eat them since humans showed up there, back at the end of the last ice age. Of course, those humans since domesticated squashes, which would obviate the need for seed dispersal — and a new genetic study of wild and domesticated squash species provides support for exactly that hypothesis.

Ed Yong has a nice write-up over at Phenomena:

[Squashes’] old dispersers were gone and the most likely substitutes were small rodents with diverse diets, who could have chiselled through the fruits and carried the seeds to pastures new. But Kistler found that these same animals are the most likely to be put off by the squashes’ bitter tastes. Compared to larger animals like elephants or rhinos, he found that smaller ones like mice and shrews have far more TAS2R genes, which allow them to taste bitter compounds.

Humans can’t stomach cucurbitacins either. People who’ve been unfortunate enough to swallow high levels of these chemicals have come down with a severe diarrhoeal illness called Toxic Squash Syndrome. But perhaps some ancient hunter-gatherers became skilled at finding individual squashes that produced low or tolerable levels. After eating such plants, they would have pooped the seeds out, inadvertently sowing the land with more palatable strains.

I am not personally a great fan of pumpkin pie, particularly since I tried sweet potato last Thanksgiving — but maybe this finding will make for some nice chatter over coffee after dinner. Unless you happen to have an uncle who’s into Pleistocene rewilding, anyway.


Kistler L., L.A. Newsom, T.M. Ryan, A.C. Clarke, B.D. Smith, & G.H. Perry. 2015. Gourds and squashes (Cucurbita spp.) adapted to megafaunal extinction and ecological anachronism through domestication
Proc. Nat. Acad. Sci.; published ahead of print November 16, 2015, doi: 10.1073/pnas.1516109112.

Classic ecology in charmingly animated rhyme

Ecomotion Studios has been working with the Ecological Society of America to produce short animated films about some of the most influential papers of modern ecology — they’re calling it “The Animated Foundations of Ecology.” Here’s the film about Robert Paine’s famous experiment in removing the top predator of tidal pool communities, sea stars, which led to dramatically reduced diversity in the other species that shared the pools.

There’s a handful more, including on one of my favorite classic ecology papers, David Simberloff and EO Wilson’s experimental demonstration of the process by which species colonize new habitats. Go check ’em out!


Paine, R. T. 1966. Food web complexity and species diversity. American Naturalist, 65-75. doi: 10.1086/282400.

Simberloff, D. S., & Wilson, E. O. 1969. Experimental zoogeography of islands: the colonization of empty islands. Ecology, 278-296. 10.2307/1934856.

23andMe will resume (some) genetic health testing


(Flickr: Nathan Nelson)

Via the New York Times, it looks like the home genotyping company 23andMe is getting the go-ahead from the US Food and Drug Administration to give customers medical information linked to their personal genetics. But not just any medical information:

The new health-related information 23andMe will provide is called carrier status. That relates to whether people have genetic mutations that could lead to a disease in their offspring, presuming the other parent has a mutation in the same gene and the child inherits both mutated genes. There will be information on 36 diseases, including cystic fibrosis, sickle cell anemia and Tay-Sachs.

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Junk science

Mating Ladybirds

Birds do it, beetles do it … (Flickr: Henry Burrows)

Last spring, the journal Current Biology published a report describing something new under the entomological sun: A genus of tiny cave-dwelling insects, dubbed Neotrogla, in which females, not males, have penises.

Or, rather, the females have a thing that they stick inside the males. Once it’s in there, that thing inflates and latches into the male with tiny barbs, binding the couple together in a copulation lasting two to three days, while the thing collects a packet containing sperm and a whole lot of (potentially) nutritious protein. What to call the females’ thing seems to have puzzled even the scientists who described it. In the text of their paper, they call it a gynosome (literally, a “female body”); but in the title, it’s a “female penis.”

This synonymy went from confusing to controversial the moment it hit the popular science press, which almost uniformly chose to go penis-first. “Female insect uses spiky penis to take charge” read the headline in the prestigious journal Nature. “Meet the female insect with giant PENIS whose steamy sex sessions last 70 HOURS,” said the Daily Mirror, caps-locked emphasis sic. Most of the stories, even the Mirror’s, got around to using the word “gynosome” eventually, and many went into more detail about how the organ in question wasn’t really a penis as we know it. LiveScience noted it was “a complex organ composed of muscles, ducts, membranes and spikes,” before adding that its size, relative to the body of a Neotrogla female, was “the equivalent of a man who is 5 feet 9 inches (1.75 meters) tall having a penis about 9.8 inches (24.9 centimeters) long.”

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Find fireflies, help keep the forests alight


Across eastern North America, one of the most magical signs of summertime is the beginning of firefly activity—hundreds or thousands of flying beetles, their abdomens glowing or flashing, filling twilight backyards and woodland clearings with floating lights.

But those displays—which fireflies put on to attract mates—are getting rarer. Or seem to be, anyway—but we don’t have the kind of comprehensive census of firefly activity that could really tell us how they’re doing. A citizen science project out of Clemson University aims to change that by enlisting anyone with a smartphone or a home internet connection:

The objective of the Clemson Vanishing Firefly Project is to promote environmental
sustainability and stewardship through the participation of local communities in environmental science research. The Clemson Vanishing Firefly Project offers a mobile app that everyone – from elementary students to seniors – can use to measure firefly populations in their communities from neighborhoods, to parks and anywhere in the world they may go!

To help, you follow the project site’s instructions for learning how to count fireflies, then use a smartphone app or a webpage form to report what you see, when, and where. Why not collect some data while you admire the lights in the forest?

(Hat tip to Erik Runquist, on Twitter.)

The Lady Gaga of ferns, and the Spartacus of ants

Friend of the blog (and former contributor) Devin Drown is wrapping up his first year on the faculty of the University of Alaska Fairbanks, where he’s been teaching the Principles of Evolution course. As a final assignment, Devin’s students are contributing posts to a class blog, Evolution, Naturally — and the first couple are great!

Margaret Oliver digs into the phylogenetic data used to support the renaming of a genus of desert-adapted, clonally reproducing ferns — after Lady Gaga. It turns out that the singer’s stage name is literally encoded in the DNA sequence that helps differentiate the new genus from its closest relatives, as Oliver illustrates in the best. Phylogeny. Figure. Ever.

(Evolution, Naturally)

Oliver’s Figure 3. (Evolution, Naturally)

Meanwhile, Alexandria Wenninger explains how some species of ants steal larvae from other ant colonies and raise them as workers — and how entomologists are discovering that those kidnapped workers can resist this unasked-for reassignment.

However, there is a growing body of evidence suggesting that the [captured workers] are not always so oblivious to their origins, as researchers observe more and more situations of what they are calling “slave (host) rebellion”. Czechowski and Godzinska, in their recent review article, “Enslaved ants: not as helpless as they were thought to be”, identify four types of rebelling behaviors, which range from aggressive acts by individual ants to a collective uprising against the parasites.

Biologist Having Too Much Fun Testing Evolution Education Game To Actually Study Evolution

Phylogenetics has never been this much fun. Seriously. (Screenshot: Evolution Lab)

Phylogenetics has never been this much fun. Seriously. (Screenshot: Evolution Lab)

NOVA, the flagship science program on U.S. Public Television, has just launched a new Evolution Lab website, which is chocked full of great information about the history of life on Earth, and how we study it. But my favorite thing has got to be the accompanying online game, which asks you to assemble organisms into evolutionary trees based on their traits and even their DNA sequences — it’s slick and pretty and it guides you into the logic of evolutionary relationships without explaining them point-by-point, unless you want that. I’ll be keeping this in mind for the next time I teach a basic class in phylogenetics.