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On March 2, 125 scientists and people affiliated with biology (from 18 countries) signed a letter to the presidents of the Society for the Study of Evolution (SSE), the American Society of Naturalists (ASN), and the Society of Systematic Biologists (SSB) See my post about this here.

Our letter and signatures, resulting largely from the effort of Luana Maroja of Williams College, was written to object to the three societies’ previously published claim that biological sex in all species (not just humans) was some sort of multidimensional social construct that was, above all, NOT binary. Here’s one paragraph from their letter, dated February 5, 2025 and addressed to President Trump and “Members of the U.S. Congress.”

Scientific consensus defines sex in humans as a biological construct that relies on a combination of chromosomes, hormonal balances, and the resulting expression of gonads, external genitalia and secondary sex characteristics. There is variation in all these biological attributes that make up sex. Accordingly, sex (and gendered expression) is not a binary trait. While some aspects of sex are bimodal, variation along the continuum of male to female is well documented in humans through hundreds of scientific articles. Such variation is observed at both the genetic level and at the individual level (including hormone levels, secondary sexual characteristics, as well as genital morphology). Beyond the incorrect claim that science backs up a simple binary definition of sex, the lived experience of people clearly demonstrates that the genetic composition at conception does not define one’s identity. Rather, sex and gender result from the interplay of genetics and environment. Such diversity is a hallmark of biological species, including humans.

I can’t resist pointing out that the “lived identity” part has nothing to do with biological sex, but shows more than anything the ideological purposes of this letter.

Although these views were presented as a “scientific consensus”, the societies did not poll their members. Rather, I gather that they consulted their executive boards and decided that this was a good way to signal their virtue—even if involved distorting biology.  Their “multidimensional, multivariate” concept of sex, which incorporates information from a number of disparate traits, is in sharp contrast with what most biologists see as the definition of sex: a binary trait in all animals and plants that is based solely on whether they have the reproductive apparatus to produce large versus small gametes.  As Richard Dawkins has explained, the latter gamete-based “Universal Biological Definition” (UBD) of sex has the advantage that, yes, it’s universal (every plant and animal species has only two types of gametes), and it’s also explanatory, essential for understanding stuff like natural selection and sexual dimorphism. The multidimensional definition is neither universal nor explanatory.

The Tri-Societies “definition”—which isn’t really a definition—gives us no way to answer the two questions, “Well, how do you tell what sex a person/animal/plant really is?” and “How many sexes are there, then?” It’s a useless construct foisted on the public to show solidarity with those people who don’t identify with one of the two biological sexes. (I repeat again that it’s a description of nature, not a a prescription about how people should be treated.) But we felt that such a letter needed to be sent to show that by no means do all biologists agree on a multivariate definite of sex.

Our first letter (identical, but with only 23 signatures) was never answered, but this time we asked for a response and got one, signed by all three Presidents.  I can’t reprint it because we didn’t ask for permission, but some of its gist is in the response below from Luana. I will say that they admitted that they think they’re in close agreement with us (I am not so sure!), that their letter wasn’t properly phrased, that some of our differences come from different semantic interpretations of words like “binary” and “continuum”(nope), and that they didn’t send the letter anyway because a federal judge changed the Executive Order on sex (this didn’t affect our criticisms). At any rate, the tri-Societies letter is on hold because the organizations are now concerned with more serious threats from the Trump Administration, like science funding.

While I can’t reveal all the points they made, I can say that I see this largely as a victory for reason, as although the letter is still up at the link (they really should remove it and inform the members of the Societies), it wasn’t ever sent and they admit that it has several deficiencies. However, since they do admit those deficiencies, they really should take the letter down because it misrepresents biological reality as well the views of many–perhaps most–evolutionists. (You can also find the letter archived here).

At any rate, the Societies’ letter was sent to all 125 signers, some of whom read this website and are able to comment on the response. In the meantime, yesterday Luana sent the letter below to the Societies (quoted with permission).  Given that the Societies admit the letter was misleading and yet it’s still on the internet representing what is said to be a “scientific consensus” and not even giving a definition of biological sex, the proper thing to do would involve either taking it down or writing something newer based on a poll of the Societies’ members.

Luana’s letter:

Dear Dan, Jessica and Carol,

Thank you for your response.  We are pleased to hear that the letter has not yet been sent . Is the letter going to be removed from the website and members notified of the change and any future changes?

I am unclear what you mean by “Subsequently a federal judge decided against the Executive Order we were commenting on, and the wording of that EO then changed, rendering our original letter moot.”  I am not aware of such change – the EO is still in place (here). What are you referring to?

Furthermore, subsequent to the Executive Order 14168, the HHS has released a guidance (here) to the U.S. government, external partners, and the public to expand on the sex-based definitions. The HHS guidance changed the definition related to “producing gametes” (at conception) to sex “characterized by a reproductive system with the biological function of producing” eggs (ova) or sperm.

We hope we can indeed find common ground,

Best,
Luana

I end by saying that scientific societies need not be “institutionally neutral” when they are dealing with issues that affect the mission of the societies, as the definition of sex surely does. But what’s not okay is for the societies to distort “scientific consensus” in the interest of ideology. I have no idea if the Presidents of these societies really believe what they said (as Dawkins has pointed out, all three Presidents use a binary notion of sex in their own biological work), but something is deeply wrong when you use one notion of sex in your own science and yet deny that notion when you’re telling politicians what scientists “really believe.”

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Please send in your wildlife photos!

Today we have part 9 of Robert Lang‘s collection of photos that he took while visiting Brazil’s region last year. Robert’s captions and IDs are indented, and you can enlarge his photo by clicking on them.

Readers’ Wildlife Photos: The Pantanal, Part IX: Birds

Continuing our mid-2025 journey to the Pantanal in Brazil, by far the largest category of observation and photography was birds: we saw over 100 different species of birds (and this was not even a birding-specific trip, though the outfitter also organizes those for the truly hard core). Here we continue working our way through the alphabetarium of common names.

Potoo (Nyctibius sp.). Our guide spotted this one at night atop a roadside post, and while the lighting made it far beyond the abilities of my big-lens Canon, my iPhone 14 managed to get a decent picture—as one of several tries, mostly unsuccessful, but this one came out:

Purplish jay (Cyanocorax cyanomelas):

Red-crested cardinal (Paroaria coronata):

Red-legged seriema (Cariama cristata):

Greater rhea (Rhea americana):

Rhea chicks:

Ringed kingfisher (Megaceryle torquata):

Roadside hawk (Rupornis magnirostris). Saw a lot of these, some of them even along the side of the road:

Roseate spoonbill (Platalea ajaja) among the caimans:

Caatinga cacholote (Pseudoseisura cristata). Formerly called the rufous cacholote (which was what our guide identified it as):

More birds to come.

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After a long ‘eclipse drought,’ lunar totality once again spans the Americas The end is in sight. If skies are clear, North and South America will witness a fine total lunar eclipse early Friday morning, March 14th. This is the first eclipse of 2025, and the first total lunar eclipse for the hemisphere since November 2022.

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The post Everything Old Is New Again, Again first appeared on Science-Based Medicine.

For the second time in a row, SpaceX lost the second stage of its Starship launch system during a flight test, while recovering the first-stage Super Heavy booster.

An X-ray signal has been detected at the very centre of the Helix Nebula, at the site of its central white dwarf star. It’s a burned out stellar remnant that doesn’t usually emit flashes of X-ray radiation but a new study has been analysing the outburst. The team of researchers think that the stellar corpse smashed into one of its surviving planets and that the X-rays are coming from the planetary debris as it falls onto the surface of the white dwarf.

An ultra-hot Neptune exoplanet has been observed by JWST and the image reveals dramatically different hemispheres. The planet orbits so close to its host start that it is tidally locked so one hemisphere remains facing the star. On this permanent daytime side, temperatures reach 2,000°C but the temperatures plummet on the daytime side. The observations show that the daytime side has bright reflective clouds on its cooler western hemisphere but not on its eastern side!

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The Gaia Hypothesis theorizes that all of Earth's systems are tied together, making one large, living organism. While there's still some disagreement about whether or not that hypothesis is true, it is undeniable that many of Earth's systems are intertwined and that changes in one can affect another. As our technology advances, we are becoming more and more capable of detecting changes in those systems and how those changes affect other systems as well. A new proposal from a robotics expert at NASA's Jet Propulsion Laboratory (JPL) takes that exploration one step further by trying to develop a system that takes the "pulse" of a planet.

Flying commercially in the US remains low risk despite a recent mid-air collision, near misses and job cuts at the Federal Aviation Administration. But aviation safety experts and former FAA employees identify warning signs that would stop them from flying in the future

Researchers have discovered techniques to bestow superpowers upon sapphire, a material that most of us think of as just a pretty jewel.

The US Department of Agriculture announced it will allocate $100 million to develop vaccines and other therapies to help contain the spread of bird flu on poultry and dairy farms

Researchers have enabled a man who is paralyzed to control a robotic arm through a device that relays signals from his brain to a computer. He was able to grasp, move and drop objects just by imagining himself performing the actions.

Researchers have enabled a man who is paralyzed to control a robotic arm through a device that relays signals from his brain to a computer. He was able to grasp, move and drop objects just by imagining himself performing the actions.