Darwin's theory. In 1859, Charles Darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. He defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".
The sentence above is true.
><span>The </span>endocrine system<span> influences almost every cell, organ, and function of our bodies.
></span><span>The endocrine system is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things. </span>
Hollow lightweight bones benefit the bird by letting it fly. If the bird had regular bones like any other animal, then the bird wouldn't have the ability to be able to fly due to the extra weight.
Using the concept that :
<span>The skin cell has twice the number of chromosomes as the sperm cell has.
</span>Hence,
<span>The sperm cell has 39 chromosomes.
The skin Cell will have = 39 x 2
= 78 </span><span>chromosomes.</span>
