Did a giraffe stretch its neck longer and longer, and then pass that long-necked gene onto its kids? No.
Can an embryo that gets a random mutation while developing in the egg/womb pass it on to their children? Yes.
This gets a bit more complicated if you really dig into it, though. Environment does change the expression of genes, and that particular sequence of genes that have been activated/shut-off/whatever can be passed on to children too.
Hence why children who were born to two shorter parents will often grow much taller than them if given much better nutrition. Or why obesity often shows up chronically in families that were poor or had limited access to healthier foods in other ways; their bodies had adapted to grab and store every extra calorie they could to guard against starvation, and unfortunately shutting that gene expression off naturally takes multiple generations.
That depends on what you mean.
Did a giraffe stretch its neck longer and longer, and then pass that long-necked gene onto its kids? No.
Can an embryo that gets a random mutation while developing in the egg/womb pass it on to their children? Yes.
This gets a bit more complicated if you really dig into it, though. Environment does change the expression of genes, and that particular sequence of genes that have been activated/shut-off/whatever can be passed on to children too.
Hence why children who were born to two shorter parents will often grow much taller than them if given much better nutrition. Or why obesity often shows up chronically in families that were poor or had limited access to healthier foods in other ways; their bodies had adapted to grab and store every extra calorie they could to guard against starvation, and unfortunately shutting that gene expression off naturally takes multiple generations.
This was a fascinating comment to read, thanks for posting 🙂