Why was Lamarck's theory of evolution discredited but not Charles Darwin's?

Branding.

Lamarck was a snooty Frenchman.

Darwin had his long beard and the Galapogos trip as part of his schtick.

Lamarck's theory was that evolutionary changes in a species are voluntary. No one has been able to prove that.

Et voilà

I am embarrassed to say I can't remember Lamarck, even after an intro biology and upper level bio psychology classes (too be fair, historical perspectives were never offered), but I was an undergrad over 35 years ago

[Quote]evolutionary changes in a species are voluntary

Voluntary implies intentional consciousness. How does this work out for for MAGATs whose simple understanding of our planet hinges on Rupert Murdoch and Steve Bannon's most extreme psychosexual fantasies of domination and nihilism? Toss Roger Stone's perversions in and you've got modern day Christianity in its full bloom.

Lamarck believed that something (something in the physical aspect of an individual) that changed by use over a creature's lifetime could be inherited by the next generation. For instance, if a man (not a gay man) were to work out 8 hours a day and consumed lots of nutrients designed to add bulk to his frame, Lamarck's theory would be that his children would inherit his bulked-out physique. But of course, we know that that is NOT how it works. Likewise, giraffe's didn't develop their extra long necks from straining to reach tender leaves at the tops of trees and aardvarks their long noses and tongues from straining to get the termites at the back of their nests.. Darwin's theory, that chance mutations increased the likelihood that certain individuals would have more success in their environments and thus their offspring would survive while others lacking that mutation would die out or be less successful, is far better at describing the natural world we live in. than Lamarck's.

Lamarck is who the battlement boys (and Eponine) are inspired by in Les Miz.

Jesus fucking Christ, R4, must you interject your hatred of Trump into everything, even a discussion of evolutionary goddamn biology?

You don't think Bannon's nihilism and Trump's nearly successful execution of his counter-evolutionary perspectives don't fit into such a discussion, r7? JFC. It's like saying we cannot discuss Pol Pot's desire to wipe out his own civilization in the context of evolutionary biology.

Bless your heart for thinking Trump even cares.

Who claimed he did?

Because there is no need to discredit Darwin. He was pretty much spot on and genetics are proving it even more so today.

Funny thing, though, is that genetics are also showing that Lamarck might not have been quite as wrong as we've thought. Epigenetics, to be precise. Epigentics is showing that there are "switches" on genes that are turned on or off by certain things that happen in a person's life. One example is starvation. If your grandfather lived through a famine, you might have a bigger likelihood of being, say, diabetic because him starving flipped some switches that stayed flipped when he passed on his genes. They think these "switches" might explain why genetically identical twins are slightly different. It's all theory right now but it's interesting.

Because Lamarck couldn't explain genetic mutation and account for the new traits appearing in species.