Zachary Elliott (@zaelefty) / X

Zachary Elliott

38.9K posts

Zachary Elliott

@zaelefty

Science educator in the biology of sex. Founder of @PdxInstitute. Author of four books. Producer of educational animations, articles, and books.

United States

theparadoxinstitute.org

Born 1998

Joined August 2014

Pinned
Zachary Elliott
@zaelefty
Nov 11, 2025
When I released Binary two years ago, the goal was to explain how sex is universally defined across species and debunk common sex spectrum arguments. It became a #1 bestseller in Biology. Now my latest book, The Sex Development Handbook, maps how sex develops in humans--from
48K
Zachary Elliott
@zaelefty
Apr 19, 2025
The level of epistemological rigor in gender ideology is simply, “I said so. Therefore, it is true.”
The Left Bible
@theleftbible
Apr 18, 2025
This. 🏳️‍⚧️
652K
Zachary Elliott
@zaelefty
Aug 6, 2023
The strength difference between male and female bodies is vast. On average, males have: - 57% more grip strength [1] - 65% more leg strength [2] - 90% more total upper body strength [3] - 162% more punch power [4] To put these numbers in comparison, males are only 7%
JRN
@JuniorRowing
Aug 4, 2023
Opinion: Trans women aren’t a threat to women’s sport contrary to British Rowing’s new policy 👇 juniorrowingnews.com/trans-women-ar…
3.1M
Zachary Elliott
@zaelefty
Jul 19, 2022
If man and woman are social constructs, then why do you need hormones and surgery to align with a social construct?
Zachary Elliott
@zaelefty
Jan 19, 2024
Replying to @IanCopeland5
Many fish can switch sex, yes. This reinforces the binary because they only ever switch from male to female or female to male. There is no third or additional sex they can switch to. It’s therefore not a spectrum. Furthermore, humans are not sequential hermaphrodites. We are
198K
Zachary Elliott
@zaelefty
Apr 17, 2025
Defining “woman” through biology is not regressive. It’s scientifically accurate. What’s regressive is thinking women can be reduced to culturally-defined roles, stereotypes, caricatures, and feelings.
165K
Zachary Elliott
@zaelefty
Sep 21, 2023
There's 5 lies that trans-identified male Veronica Ivy utilizes in this clip about biological sex and sport. Let's break it down. 1. "Policing whether transgender women and intersex women are really female is built in racism." While there has been historical racism against
Mythinformed
@MythinformedMKE
Sep 21, 2023
The transgender self-imposed struggle session that Trevor Noah is undergoing here is priceless. He knows men aren’t women, squirms and squirms.
Jeremy Shaw, MD
00:00
Jeremy Shaw, MD
1.2M
Zachary Elliott
@zaelefty
Apr 24, 2025
I’m still waiting on @Femi_sorry to apologize for posting a graphic I made, not attributing it, and then using it to argue for the very thing it was created to debunk.
Is Sex Bimodal? — Paradox Institute
From theparadoxinstitute.org
335K
Zachary Elliott
@zaelefty
Mar 11, 2025
So you can use the word “men” no problem but can’t be bothered to say “women”?
249K
Zachary Elliott
@zaelefty
Jan 1, 2024
Replying to @CaptAmazo
The shedding of the uterine lining IS the period. The cause is the hypothalamic-pituitary-ovarian (HPO) hormonal axis interacting with the uterus to induce the shedding. Only females can have this.
116K
Zachary Elliott
@zaelefty
Sep 22, 2025
Hi Natalie, In your graphs here, I can’t help but notice that there are just two sexes listed there, “male” and “female.” And that there are only two colors, with blue representing males and red representing females. It seems this is the binary you’re missing.
Natalie Bennett
@natalieben
Sep 21, 2025
Nature does not do binaries. Anyone who tells you biology is simple is wrong phys.org/news/2025-09-s…
Readers added context
The graphs in the posted link show the sex binary (male or female) and bimodal distribution graphs, disproving the poster’s claim. Sex in mammals is binary and immutable. ncbi.nlm.nih.gov/books/NBK9967/ phys.org/news/2025-09-s…
291K
Zachary Elliott
@zaelefty
May 8, 2025
If there is no biological difference between men and women then how are babies made?
Independent Women
@IWF
May 7, 2025
“Is there a biological difference between men & women?” -@RepLisaMcClain “The answer is NO.” WHAT⁉️
00:00
184K
Zachary Elliott
@zaelefty
Jul 26, 2023
And yet, curiously, males produce 15-20 times more testosterone than females. The gap is so large in fact, that the highest T levels in females are still 5 times lower than the lowest T levels in males. So, while T is present in both males and females, it is in far different
374K
Zachary Elliott
@zaelefty
Oct 25, 2022
Dylan Mulvaney is not trans. He’s literally a trained actor who’s found a way to get attention. His “Day X of being a girl” series is a never-ending list of heavily caricatured jokes about sex stereotypes. This is not a serious person with gender dysphoria.