You all are still stuck on the old evolution theory. Many changes and ideas have been proposed since then.
First of all, evolution is a both a fact and a theory. Microchanges (microevolution) amongst creatures are factually observable primarily in microbes, which helps us to develop antimicrobials. What people differ on in opinion is in the region of macroevolution, mainly the reliability of the Darwinian tree of life, which is the basis of the idea of Universal Common Ancestry (UCA). So no, evolution is not a fact in this regard.
With more and more studies, there is a growing doubt among scientists (mainly biologists) about the reliability of the Darwinian tree of life. In return, alternatives such as the tangled tree of life and web of life are being more emphasized.
"We have no evidence at all that the tree of life is a reality," says Bapteste, an evolutionary biologist at the Pierre and Marie Curie University in Paris, France. [
1]
"Was it not already obvious, from the discovery and deciphering of DNA, that all life forms are descended from a single common organism—or at least a basal species? No, says Douglas Theobald, an assistant professor of biochemistry of Brandeis University and author of the new study" [
2]
"The tree versus web debate remains "very controversial right now in evolutionary biology," Theobald says, reluctant to pick a side himself. " [
2]
Also, the idea that shared DNA implies common ancestor is not necessarily true.
"Most people and even scientists operate under the premise that genetic similarities imply a common relation or ancestor. But as with similarities in physical appearance or structure, these assumptions "can be criticized," Theobald notes." [
2]
You also have to know that the method that favors the UCA relies on the premise that the tree of life is in fact true. This inherently induces bias which can explain why many scientists still favor this pillar.
"We show that the alignment gives a strong bias for the common ancestor hypothesis, and we provide an example that Theobald's method supports a common ancestor hypothesis for two apparently unrelated families of protein-encoding sequences (
cytb and
nd2 of mitochondria).
This arouses suspicion about the effectiveness of the “formal” test. " [
3] says Masami Hasegawa, a well-known biologists in China, in his study titled
"Some Problems in Proving the Existence of the Universal Common Ancestor of Life on Earth".
One of the leading evolutionist in this 20th Century, Masatoshi Nei, has proven in his study that the reliability of the tree of life is not universal as can be seen in the Phylogenetic tree of MHC class II b chain genes in mammals.
"We then show that if the tree is to be reliable, both Pb and Ps must be high... Figure 4 represents the opposite case, where Pb is low for most interior branches of the tree" [4]
These studies open more possibilities that human might have an independent ancestor to those of other animals.
