![]() ![]() ![]() It’s made of tiny blood vessels and nerve tissue. Pulp is the innermost portion of the tooth. Gums, also called gingiva, are the fleshy, pink connective tissue that’s attached to the neck of the tooth and the cementum. It forms the line where the cementum (that covers the root) meets the enamel. The neck, also called the dental cervix, sits between the crown and root. The jaw bone, also called the alveolar bone, is the bone that contains the tooth sockets and surrounds the teeth’s roots it holds the teeth in place. Blood vessels supply the periodontal ligament with nutrients, while nerves help control the amount of force used when you chew. Along with the cementum, the periodontal ligament connects the teeth to the tooth sockets. It contains both nerves and blood vessels. The periodontal ligament is made of connective tissue and collagen fiber. It’s connected to the periodontal ligament. Also called cement, this bone-like material covers the tooth’s root. The root canal is a passageway that contains pulp. It makes up approximately two-thirds of the tooth. A species can split into two or more descendant species and they can split again and again across the generations.ĭr Paul Willis is the Director of RiAus and formerly a presenter on ABC TV's Catalyst program.The root is the part of the tooth that extends into the bone and holds the tooth in place. The same thing happens in evolutionary families. "The answer is of course that your grandparents had more than one child and they each went off and started their own families creating new branches of your own family tree." "The fallacy of linear evolution is most clearly illustrated by the analogy of asking how can I share common grandparents with my cousins if my cousins and my grandparents are still alive?," says Dr Willis. "The idea of sharing a common ancestor leads to the second major misunderstanding inherent in the question," says Dr Willis, "that evolution is a linear process where one species evolves into another."Įvolution is really a branching process where one species can give rise to two or more species. Chimps and humans share between 98 to 99% of DNA suggesting that we shared a common ancestor around 6 million years ago. Humans are actually more closely related to chimpanzees and other apes, but DNA evidence again shows that we didn't evolve from them. ![]() Similarly, the fossil record has identified ancestors common to both humans and monkeys, such as an as yet unnamed primate fossil from Myanmar found in 2009 and dated as living around 37 million years ago. Based on the similarities and differences between the two types of DNA, scientists have estimated that humans and rhesus monkeys diverged from their common ancestor 25 million years ago. A 2007 study showed that humans and rhesus monkeys share about 93% of their DNA. This evolutionary relationship is supported both by the fossil record and DNA analysis. Instead, monkeys and humans share a common ancestor from which both evolved around 25 million years ago. "But the question itself reveals a couple of fundamental misunderstandings about evolution and how it operates", he says.įirstly, humans did not evolve from monkeys. ![]() "This is a question often encountered by evolutionary biologists," says Dr Paul Willis, palaeontologist and Director of RIAus. With all the 'monkeying around' that can go on in the playground or even in the office it seems we could easily be directly descended from monkeys, but our evolutionary relationship is actually much more distant. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |