Lamarck’s theory was that if an organ or a body part ( arm, neck, leg…) was used a lot, it becomes stronger and if it wasn’t used it would get weak so he thought that these changes would be passed to their offspring.
For example a giraffe uses its neck to obtain food but some day the giraffe wouldn’t be tall enough to catch its food so he would have to stretch his neck and it would get stronger and longer, then baby giraffes would inherit longer necks.
But his theories were disproved by experiments and are no believed because physiological changes can’t be passed through genes because only changes on genes can be passed on.
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information of biodeluna