What is a spandrel in evolutionary biology?

An evolutionary spandrel is a physical structure or behavioural characteristic that is a by-product from some other functional adaptation.

What is considered vestigial?

Structures that have no apparent function and appear to be residual parts from a past ancestor are called vestigial structures. Examples of vestigial structures include the human appendix, the pelvic bone of a snake, and the wings of flightless birds.

What is the difference between an atavistic and a vestigial trait?

Atavism is old (from evolutionary past) functions being turned back on and/or structures reappearing. Vestigial structure is one that (seemingly) is no longer needed but still persists in the organism.

Is consciousness a spandrel?

Instead of an adaptation, consciousness might be a spandrel (in the sense of Gould and Lewontin Reference Gould and Lewontin1979)—a by-product of some other trait that has adaptive value although consciousness itself has no adaptive value of its own (or may even be dysfunctional).

What is a spandrel in architecture?

spandrel, also spelled spandril, the roughly triangular area above and on either side of an arch, bounded by a line running horizontally through the apex of the arch, a line rising vertically from the springing of the arch, and the curved extrados, or top of the arch. Example of a spandrel on a building in Chicago.

What is the difference between adaptation and Exaptation?

While adaptation refers to a feature produced by natural selection for its current function (e.g. echolocation in bats), exaptation has been defined as a feature that performs a function but was not produced by natural selection for its current use (e.g. feathers that might have originally arisen in the context of …

Why is coccyx vestigial?

The coccyx or the tailbone: Obviously, humans no longer have visible external tails, because the current version of humans do not need tails to live in trees as earlier human ancestors did. The coccyx currently serves as an anchor for muscles; that wasn’t its original purpose, so that’s why it’s considered vestigial.

What are atavistic features?

Atavistic Form Features of sex offenders: thick lips and protruding ears. Features of women offenders: shorter and more wrinkled, darker hair and smaller skulls than ‘normal’ women.

How are vestigial structures and Atavisms alike and different?

Vestigial structures are homologous of organs that have lost all or most of their original function in a species through evolution. Atavism is the recurrence of a trait after an absence of one or more generations due to a chance recombination of genes.

What is a spandrel beam?

Definition of spandrel beam : the exterior beam in steel or concrete construction that marks the floor level between stories.