Collagen is a part of the connective tissue that in the skin helps in firmness, suppleness and constant renewal of skin cells. Collagen is vital for skin elasticity. Ligaments are another type of connective tissue that attach two bones and consequently hold the joints together.
There are at least 33 phyla (plural of phylum) of animals. Humans are members of the phylum Chordata. All of the chordates have elongated bilaterally symmetrical bodies. That is to say, the left and right sides are essentially mirror images of each other.
Due to billions of years of evolution, humans share genes with all living organisms. The percentage of genes or DNA that organisms share records their similarities. We share more genes with organisms that are more closely related to us.Humans belong to the biological group known as Primates, and are classified with the great apes, one of the major groups of the primate evolutionary tree.Besides similarities in anatomy and behavior, our close biological kinship with other primate species is indicated by DNA evidence.NA is thus especially important in the study of evolution. The amount of difference in DNA is a test of the difference between one species and another â and thus how closely or distantly related they are.