Around 100,000 years ago there was a second hominine species closely related to modern humans, Homo <span><span>neanderthalensis,</span><span> or commonly called the Neanderthal</span>.</span> Recent studies of neanderthal DNA have shown that there is 3-4% of their genes in modern humans outside of Africa, mostly from Europe, including the ones for adapting to the cold and vitamin D absorption.
100,000 years ago is your answer
The previous statement is true because if a substance cannot get into a cell membrane it is assisted via protein channels however if it doesn't need the protein channels then it just flows through the membrane.
Cell- <span>the smallest structural and functional unit of an organism, typically microscopic and consisting of cytoplasm and a nucleus enclosed in a membrane. Microscopic organisms typically consist of a single cell, which is either eukaryotic or prokaryotic.</span>
