What can homologous structures tell us about evolution?

Question

My teacher is asking this question on an essay test and I need help coming up with an answer. Please help me! I don't know what homologous structures are or really much about evolution.

Answer 1

It's called finding a similarity and then making up a story about the past.



Do we see similarity in the anatomy and physiology of different animals? Sure we do. Evolutionists like to argue that these similarities prove that all life evolved from a common ancestor (common descent).



First of all, there are plenty of problems—like homologous structures that are not produced by homologous genes or the same embryological development, or homologous structures in animals that are not suppose to have a close common ancestor (no evolutionary relationship)—extreme convergent evolution is a real problem, and so forth.



But the thing is, homology can just as easily point to a common designer; it fits quite comfortably with the creation model. As Dr. Don Batten has said, “Think about the original Porsche and Volkswagen ‘Beetle’ cars. They both had air-cooled, flat, horizontally-opposed, 4-cylinder engines in the rear, independent rear suspension, two doors, trunk in the front, and many other similarities. Why did these two very different cars have so many similarities? Because they had the same designer!”



And as Dr. Jerry Bergman said, “...the requirements of life are similar for similar living things, and some designs are preferred in constructing animals because these designs are superior to competing designs. All automobile, bicycle and pushcart tires are round because this design is superior for the function of most tires. A tire homology does not prove common descent, but common design by engineers throughout history because of the superiority of the round structure for rolling.”



It has been asked, “Do evolutionists conclude that bicycles, cars, and airplanes all have wheels because they all started out as tricycles?”



Dr. Carl Weiland said, “By its very nature, creation involves the intelligent application of design information, which it would seem logical to conserve. For example, if the pattern of the forelimb bones in a frog works well, following good bioengineering principles, then it would seem reasonable for the same principles to be used in the other creatures, modified to fit their particular needs.”



Similarities should be expected among creatures that are designed to drink the same water, eat the same food, breathe the same air, and live on the same terrain.



Evolutionists love to arrange animals or body parts into cladograms or simplistic line diagrams to give the impression of evolutionary lineages (which they are constantly having to rearrange by the way). But you can arrange a collection of teaspoons in a cladogram. What does that prove? Nearly anything can be put in an order, such as: tricycle, bicycle, motorcycle, car, airplane, space shuttle. Lining up objects or organisms does not explain how they came to be, nor does it demonstrate that natural selection is responsible.

Answer 2

Homologous Evolution

Answer 3

Homologous structures derive from the same embryonic tissue. Structures which perform the same function, but derive from different tissues are analogous.



Starting from the shoulder, the wing of the bird has the same order of bones as a human arm:one long bone, then two, a group of small bones then five digital rays. The are homologous, as are the forelimbs of every land vertebrate. On the other hand, the wings of the dragonfly have no bones; that is analogous. The commonality of structure and the variations in growth (especially where adults don't have limbs) show how the fin of an ancient fish could produce so many vertebrates.



Look at animal horns and related structures. Some are bone; some are covered in skin; the horns of the various rhinoceroses are hairs. (The ossicones of giraffes and okapis indicate what a short-necked giraffe would be like.) Look at how the different horns relate to other structures and patterns of common ancestry emerge.

Answer 4

A homologous structure is a structure that is the same structure but different function. The opposite of that will be an analogous structure which is a structure that has a different structure but same function.



Example for homologous: a chicken wing is a homologous structure to a bat wing.



Example for analogous: a flying bird wing is a analogous structure to a bat wing.

Answer 5

Homologous structures share characteristics regarding their construction, such as the arrangement of bones, because the species carrying those structures evolved from a common ancestor. So a bird's wing and a bat's wing are homologous because birds and bats both evolved from an ancestral tetrapod that had the same basic bone structure in its front limbs. The existence of that similar bone structure in both kinds of wings is evidence that they are homologous.



Birds wings and insects wings are analogous. Both types of wings evolved independently, rather than from a structure possessed by a common ancestor.

Answer 6

Any structure that is conserved (homologous structures) between different species means that the common ancestor of those species also had a similar structure and it was therefor conserved through evolution.