- The two species i picked that demonstrate a shared homologous trait are humans and monkeys. The trait shared between the two species would be the tailbones. We as humans do not have actual tails like monkeys do, but we share that same bone. We have evolved so that our 'tails' are not physically present outside our body any more and they don't typically have a use anymore,and they don't grow to the full extent like a monkeys does. This bone helps hold our muscles in place in that area(including the spinal column), and it helps us to put to use the muscles in that area for us as humans to eliminate waste correctly, and for monkeys it does the exact same. Some say that the tailbone in humans is considered to be 'vestigial', but i would disagree because our body still needs and uses the bone today. Monkeys have more free range you could say with their tail bone because their tail is connected through it and they can use their tails for many things, so to have that base bone is very important for them as well.
- Although we share the same tailbone with humans and monkeys, they are slightly different in the way they are used. for example, our tailbone is apart of a spinal column and like i said before it is used to hold muscles in place and muscles for waste elimination. It is a vertebrae at the bottom of the spine. For monkeys, their tailbones are considered to be the base of their balance, because they use their tails to grab things, hold onto things and to be centered.
- It is said that chimpanzee is the common ancestor between humans and monkeys. The chimpanzee does have a tailbone just like humans and monkeys do. The chimpanzees though have a bigger pelvis than humans and their spinal column isnt as long as humans.
HUMAN
MONKEY
CHIMPANZEE
Analogous Trait:
- The two species i picked that demonstrate a shared analogous trait is the human and the octopus. The trait shared between the two species would be the eye. Like humans, an octopus also has two eyes. These are considered to be an analogous trait because the two species are not anywhere near the same or similar really at all for that matter, but our eyes are very similar with each other. Octopus's are marine animals that have different organs than us, different skin, different body parts etc. In some ways the octopus has the advantage with their eyes. They dont have a blindspot unlike humans do, meaning that an octopus can see everything that is going on around them, so with that, thy are more aware and cautious. An octopus eye also has more photoreceptors than a human eye, meaning they have much better vision than humans.
- Although yes we share the same trait with an octopus, we as humans have another advantage with our eyes than an octopus has with theirs. first off, we can see in color. So that means that they can only tell the difference between light and dark. Our eyes are similar in structure based off that we both have eyelids, corneas, pupils, iris, ciliary muscles, lens, retina, optic nerve, and optic ganglion and they both resemble each other.
- I couldnt find the common ancestor between the octopus and human, but i do know that we last shared a common ancestor 500 million years ago.
While I appreciate the very thorough description of the two traits for your homologous section, the opening section in both the homologous and analogous areas asked for a description of your species, not just the traits you are comparing. This would help your reader understand the environment and behavior of the species to better understand why their traits evolved the way they did.
ReplyDeleteGood job in the next section focusing on the functional/structural differences in your homologous traits.
"It is said that chimpanzee is the common ancestor between humans and monkeys."
No. That's false. The chimpanzee is a modern species of ape, so it cannot have given rise to two other modern species. Moreover, monkeys arose before apes, so an ancestral ape could not give rise to monkeys. You need to map out the family tree of primates to see this pattern.
Both humans and monkeys are primates, so we know that the common ancestor was an ancestral primate. We know from fossil records that early primates possessed the ancestral tail structure common in all primates, with changes occurring (primarily in humans) to produce altered structures as a result of different environmental pressures.
By the way, why did apes lose their tail structures? What environmental pressure produced this trait?
Good images.
The eye is a classic analogy example. Good choice.
You seem to focus on the "advantages" of human eye sight over octopus eye sight. Was there a way to do this without the bias toward our own species? Could you describe differences in general? Are there any advantages of the octopus eye structure vs. the human structure? Humans have a blind spot due to the positioning of our optic nerve. The octopus doesn't have a blind spot. Isn't that an advantage for the octopus structure? Additionally, does the octopus need color vision? They tend to live in deeper waters where color is severely muted, if distinguishable at all. Detail is more important than color, and that is what the octopus possesses in it's structure.
The question on ancestry is less concerned with a specific ancestor than how you can use ancestry to confirm that these are analogous traits. The information for these traits that confirm analogy is genetic in nature, with the genes that shape the octopus eye being distinctly different from the human eye, confirming that these did not arise from a common genetic origin from their common ancestor.
Good images.
Hello there! I really enjoyed reading your post. You did a really good job noting the differences in the structure between the tail bone of a monkey and of a human. I noticed you focused on chimpanzee which is also a primate like humans, but i do not think they are the common link actually.It also would have been interesting to see you maybe compare different types of monkeys instead of just monkeys in general.
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