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- Hacker News
- "Some day, your immune system may decide to attack your pancreas."
Immune attack of the pancreas is usually a disease of youth. Type 2 diabetes which is overwhelmingly the diabetes associated with aging is not an autoimmune disease.
by epcoa - The article complains about a lot of questionable design aspects of the human body, including menopause. Only us and a couple of whales (and apparently one specific chimp population I wasn't aware of?) go through menopause, making us infertile long before we die. Why is that? Wasn't more kids supposed to be better?
I recently learned about this (not sure if it was a YouTube video or an article): apparently, it's not that we become infertile long before we die, it's that we live long past our fertility ends. And the reason for that is really simple: old people have accumulated a lot of knowledge that is valuable to teach to younger generations. The alternative is not to be fertile longer, but to die younger.
Presumably, menopause only occurs in species that learn and teach, and are able to accumulate so much knowledge that it becomes useful to keep experienced individuals alive longer so they can continue to teach.
by mcv - > Brains. After you reach adulthood, neurons don’t divide. If some of your neurons die—which happens every day—then they’re gone. If you get a brain injury, the other neurons will try to “learn around” the injury, but the neurons themselves are never replaced.
This is a very outdated view. Neuroscience has shown that neurogenesis continues throughout the entire life span of humans, albeit at a much slower rate. You might have a hard time recovering from a serious brain injury or stroke but losing a few brain cells won’t change a thing.
- > And even after taking [immunosuppressants], there’s a 30% chance the kidney will be rejected within 10 years. This is not helpful.
To the author: thank you, you made my day. It had been a very, very long time since I last read an article on the Internet that felt written by a human being - with humor, some poetry, and science.
by Noe2097 - I have first-hand experience! My immune system slowly killed my liver (primary sclerosing cholangitis), and I had a transplant. (btw, for $0, thank you to the Australian health system)
I received a cut-down liver from the donor; I got the bigger lobe, a child recipient got the other lobe.
Within a few months of transplant, the new liver had regrown, but (probably because of the transplant orientation) rather than growing across to the left, it grew down the side of my body.
It's all good and functions fine, it's just that now my right-side of my body isn't as 'saggy' as my left because of the area it grew in to.
It's an amazing organ, and it truly sucks when you don't have a well-functioning one.
by frostysonic - The author suggests humans are overturned to repairing skin and blood, but I strongly disagree. People with problems with wound healing can face significant disability and mortality. Wound healing allows us to have surgery and close up with simple sutures. A lot of complications post-surgery in humans and other animals are specifically from impaired wound healing capability. It’s a good trade-off: nearly everyone will eventually get cut open by accident or on purpose. The skins ability to heal is so amazing that many types of wounds require nothing other than some cleaning, the body will fully clot, bridge, build, and scar back to most retained function. Wound healing allows us to heal large burns and even simply leave many wounds open to air.
Complications with healing are pretty brutal. Necrosis, amputation, infection are all common without the built-in cascade we have.
- Most of the body doesn't regenerate because there was not enough evolutionary pressure. Even with regeneration you could still easily die from some severe injury, blood loss or disease. While salamander regeneration is impressive, it has its limitations. For example, no known adult salamander can regenerate an entirely removed eye. Also if you chop a salamander, it will not regenerate like a Planarian worm, it will just die. And a fun fact, Axolotls can regrow a limb yet cannot regenerate an adult eye lens.
Also, although the article is mostly true, there are some inaccuracies:
>> Neurons and cardiac muscle cells don't reproduce after childhood
There is some evidence showing a slow cell turnover in cardiac muscle, estimated around ~1% per year in young adults, falling toward ~0.5% in older people. Most neurons don't regenerate, but there an evidence that some parts of the adult brain (such as hippocampus) still produce new neurons, although the number is very low.
Liver regeneration is not perfect either: https://www.youtube.com/watch?v=rOv7Sr3X-eo .
by senfiaj - Hi, your friendly, local pathologist here. I'm the kind of doctor that diagnoses liver diseases, cancer, lots of infections, inflammatory processes, benign tumors, and runs the lab that a lot of other doctors use the results from to inform a lot of their other decisions.
If you really want to learn about this stuff, Robert Weinberg's The Biology of Cancer is where to start. It introduces concepts starting where a high school student could understand and carefully walks through the history of our development of knowledge until, by the end, the pithy chapters are helping novel concepts for real science flower in your brain all on their own. It's the best book of biological science I have ever read. 10/10, will read again.
by 0xWTF