Because some trees are extremely old and just don’t die, and I’m in need of some answers.
In: Biology
They do.
When they an OAK tree can last for 300 to 400 years, the reason is aging. Every living organism (including plants) are made of living cells. Every cell has its age. After which it dies. New cells take the place. The process (of replacing old dying cells) does not continue forever. The tissues deteriorate over a period of time. In plants (or trees) the capillaries that form the tunnel (series of tunnels actually) to transport water, minerals, food, etc – wear out after some time. Then replacement of cells/tissues slows down and/or stops. However, many times the death will happen when they get too old to survive and are diseased by fungus, borers, water splash & heavy winds. Plants die.
Human cells have a maximum limit they can replicate called the Hayflick limit. Once this limit is reached you cannot create any new cells to replace the old ones if they are damaged. As far as i know trees do not have this limitation.
A hazel tree will last about 80 years but if you cut it down to a stump every few years it will regrow and it will last pretty much forever.
Not really, but neither do humans.
But before we get into that let’s show why you can’t compare a plant to a complex animal like a mamal, like a human.
Many trees that we like and cultivate are from cuttings of the trees we like, and thus are a type of clone. If theres one “variety” of apple you like, remember that it’s actally all from one tree and cloned over and over (granny smiths are all the same one tree and are not a parent/child type reproduction). If you plant an apple seed, the resultant tree would be different than the parent, but a cutting is not.
That difference in reproduction methods is important. The fact that cuttings/clones are viable is caused by the way plants live, with each section of the organism able to grow all the other parts. You can plant the root or the trunk and it’ll grow the missing parts, meaning no one part is absolutely critical.
A human can only be reproduced one way, from the seed. You can’t nuture a kidney to grow a whole person, and a person cannot live at all without a kidney. We have dozens (hundreds?) of critical parts which we need 100% all of them to continue living.
Why is this distinction important?
(ELI5 version) Age is the process of DNA splitting and copying 99.99999999% over and over all the time. It’s not perfect, and thats why we age. Once our DNA for kidneys is too far off to continue functioning, they shut down and we die. The same happens to our liver, heart, lungs, brain… There are lots of ways that age can kill us, but it’s not the age directly, it’s just the consequences of age.
If a tree has a group of cells that can mo longer perform as needed, other cells can just grow and replace it because as discussed, a whole tree can be grown from any one part. It’ll never have a failing heart, kidney, or lung, not just because it doesn’t have them, but because it doesn’t need them to live.
edit: aging is actually much more complex than this, but I was trying for super simplified, for more info ask about telomeres. Also not all plants can be grown from cuttings, it was just the example used to show the enormous differences between fauna and flora.
Latest Answers