Let's talk about why mammalian red blood cells (erythrocytes) don't have nuclei.

~85% of all your cells are erythrocytes, 20-30 trillion of them in an adult.

You produce >2 million every second & they represent half of all your blood volume. So why don't they have any DNA?
We can talk about the ways that erythrocytes are optimized for transporting hemoglobin(Hb)-bound oxygen throughout our tissues:
No nuclei means no metabolism or cell machinery, so an RBC becomes just a small, flexible bag of Hb, which means they can travel down even the tiniest of blood vessels, and deliver oxygen payloads into the interstitial spaces.
The puzzle here is that almost all non-mammalian vertebrates have nucleated RBCs, with very rare exceptions.

1. T Ryan Gregory (@TRyanGregory) proposes one explanatory mechanism:
Nuclei take up space in a cell and the larger the genome, the more space (see figure, showing fish correlation). That may impose cap on how large a genome can get in a vertebrate w nucleated RBCs before they get too big to travel to the smallest spaces in tissues.
Large genomes, especially those with extensive non-coding sequences, require a decoupling of that relationship.

His paper is here: pubmed.ncbi.nlm.nih.gov/11783946/ (paywalled)
2. It's also worth noting some things that cells without nuclei (anucleated) *can't* do
a. They can't be infected by viruses.
b. They can't develop mutations or cancer.
c. They don't need to be told to self-destruct when they malfunction.
So one possible explanation derives from Peto's Paradox: anucleated cells may be one of many adaptations to 'largeness' in organisms, where cancer rate and number of cells should be roughly correlated.
3. What's the upside of nucleated erythrocytes?
In non-mammals, RBCs are part of their immune system. They present antigens, respond to viral infections by producing interferon, some can phagocytize yeast & they surround or "rosette" invaders to signal macrophages to respond.
It could be that the mammalian immune system co-opted those functions into other, more specialized cell types (although human RBCs do still have some immune function).
Conclusion:
Mammals made a trade-off in evolutionary history that 85% of cells have no DNA, are metabolically dead & can't adapt to their environment.

In exchange, we likely constrained our cancer risk, limited infection & reduced metabolic "cost" of our large blood volume.

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More from @c0nc0rdance

3 Sep
Let's talk about where 'liberty' comes from.

Roman god 'Liber', god of the vine & male fertility, was later merged with Bacchus. He was son of Ceres, brother/consort to Libera.

Liber pater ('Free Father') was patron god of plebians, patron of male virility & boys becoming men.
A Liberalia was a festival of the cult of Liber Pater & it was celebrated when boys took manly toga virilis w phallic symbols & "a giant penis on a trolley".

Liberalia celebrated drinking, free speech & overthrow of political structures, making cult dangerous to establishment.
The point is that Liber Pater was in favor of the poor & powerless getting drunk & overthrowing leaders. He was a god of anarchy & plebian values.

In late Republic, Cicero was careful to say that "Liber was not identical to Bacchus": rebellion & equality, not chaos.
Read 4 tweets
3 Sep
Let's talk about Barbara Jordan, Texas lawyer, politician & civil rights leader.

Born Feb 21st, 1936 in Houston's 5th Ward, daughter of a Baptist minister.

Barred from attending Univ of TX by segregation, she graduated Texas Southern University magna cum laude. Image
During her time at TSU (historically black university in Houston), majoring in political science & history, she led their debate team to national championship.

She graduated Boston University School of Law in 1959 with JD, taught Political Science at Tuskegee Institute in AL. Image
After 2 unsuccessful bids for state rep, she won a seat in Texas Senate in 1966, the 1st Black Senator since 1883, and the 1st Black woman.

Re-elected, she served until 1972, was the 1st Black Senate pro tempore, and on June 10, 1972 sworn as Governor of Texas for a single day. Image
Read 7 tweets
28 Aug
If only there were some way to know what the Founding Fathers thought of vaccines and vaccine mandates?

Oh, right, they wrote extensively on the subject, and by their actions showed their commitment to public health.
(thread)
You may know the history of Washington's variolation of troops at Valley Forge, making them immune to the smallpox scourge that led to tragedy at the Battle of Quebec. The process was not without risk, but according to figures, inoculation lowered case fatality from 45% to 2%.
During the war, he also mandated quarantine for civilians and soldiers under his direction, enforced by troops and general order.
Read 11 tweets
17 Aug
I did a study abroad semester in Italy, near Florence, & one course involved field trips to all the major cathedrals in Tuscany and Umbria, led by the professor of architecture from the local uni; a native Florentine.

One idea he introduced has always stuck with me:
"A cathedral is a bridge between Man and God. The columns rise up like bridges into the sky, to cast our gaze upwards to beauty, art & the unachievable perfection of Heaven."

The walls below are minimally adorned, the ceiling elaborate and ornate... to make us cast our eyes up.
The separation of sacred & perfect from human & mundane speaks to the beliefs of the people who created these buildings and their unconventional, even impractical designs.

They were building bridges to Heaven, a place for gods to reside.
Read 7 tweets
17 Aug
Now that we've defined the Discovery Institute's 'Wedge Strategy', let's talk about how it's become the model for infiltrating public consciousness with poisonous ideologies.

Let's focus on how it's used in anti-vaccine movements first.
There was a change in tone around 2004 in the anti-vaccine movement. Jenny McCarthy and Robert Kennedy Jr. began using talking points like:
"Green our vaccines!" (remove mercury & aluminum)
"Too many, too soon!"
"I'm not anti-vaccine, I'm pro-SAFE vaccine.
The goal is to locate pre-existing soft points. Conceal your true intentions by hiring a messaging expert to change the conversation. Not pro- vs. anti-, but unsafe vs. safe; or "more research needed".

The goal isn't to convince experts or scientists. It's to muddy the water.
Read 7 tweets
16 Aug
Let's talk about "The Wedge Strategy" as it applies to creationism, vaccines, and science denialism of all stripes.

The name derives from a document drafted in 1998 by staff at the Discovery Institute & marked "Top Secret" and "Not For Distribution", leaked by an HR contractor.
It made explicit the aims and strategy of the Discovery Institute's Center for the Renewal of Science and Culture, a group led by Stephen Meyer that rebranded creationism as intelligent design.
Their goals, stated plainly:
"To defeat scientific materialism and its destructive moral, cultural and political legacies"
"To replace materialistic explanations with the theistic understanding that nature and human beings are created by God"
Read 9 tweets

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