William Aird: Why Did Mammalian Red Blood Cells Give Up Their Nucleus?
William Aird, Professor of Medicine at Harvard Medical School, shared a post on LinkedIn:
“Why did mammalian red cells give up their nucleus?
Most cells protect their nucleus.
Mammalian red cells do the opposite.
They eject it.
At first glance, this looks like a loss.
No DNA, no repair, no division. A finite lifespan.
But it is better understood as a trade-off.
Removing the nucleus allows the cell to remove something else too:
its mitochondria.
And with that, a potential conflict of interest.
A red cell that carries oxygen but also consumes it would compete with the tissues it serves.
By giving up mitochondria, the red cell commits fully to delivery.
It does not use the oxygen it transports.
It gives it away.
That same simplification has other consequences:
- more space for hemoglobin
- greater deformability in narrow capillaries
- fewer intracellular obstacles to diffusion
- educed capacity to support viral replication
But the central idea is this:
the red cell becomes a specialist by subtraction.
It gives up autonomy to eliminate internal competition and to optimize a single function.
Not every organism makes this choice.
Other vertebrates retain nucleated red cells.
Their constraints are different.
Mammals chose another path.
One that favors efficiency of delivery over cellular independence.
What looks like loss is the elimination of internal conflict.”
Read more on The Blood Project.

Find more posts featuring William Aird on Hemostasis Today.
-
May 29, 2026, 17:23Rita Schwab: Current Clinical Management of Trauma without the Use of Allogenic Blood Products
-
May 29, 2026, 17:22Brian Schiro: Excited to Provide Guideline Based Care at the Aortic Center
-
May 29, 2026, 17:20Martin Widschwendter: How Molecular Detection Tests Could Transform Endometrial Cancer Care
-
May 29, 2026, 17:18Nina Lansbury: Supporting a Period Friendly World With Menstrual Health Research and Education
-
May 29, 2026, 17:16Ipsita Chatterjee: Red is Not Shame, Red is Power, Red is a Woman
-
May 29, 2026, 16:49Abdulrahman Nasiri: The Evolving Role of Romiplostim in SAA
-
May 29, 2026, 16:46Soumen Bhattacharya: UC-II and Immune Modulation in Osteoarthritis
-
May 29, 2026, 16:38Ana Pedrero Gil: Red Blood Cell Transfusion Practice in Spain – High Inappropriateness Despite Low Overall Use
-
May 29, 2026, 15:40Lena Volland: Expanding Holistic Care in Bleeding Disorders Through Pelvic Health Physical Therapy at WFH Congress