How the Zebra got its stripes.

[old man emu]

We all know about the English mathematician, Alan Turing. He's the bloke who was very instrumental in developing a machine to decode German military messages created using Enigma machines. But what did he do after the war ended? Well he want back to being a mathematician working on developing computers. However, he must have got bored with that field of study. When Turing was 39 years old in 1951, he turned to mathematical biology, finally publishing his masterpiece "The Chemical Basis of Morphogenesis" in January 1952.  "The Chemical Basis of Morphogenesis", which describes how patterns in nature, such as stripes and spots, can arise naturally and autonomously from a homogeneous, uniform state. https://en.wikipedia.org/wiki/Turing_pattern

 

Turing proposed a model wherein two homogeneously distributed substances (P and S) interact to produce stable patterns during morphogenesis. These patterns represent regional differences in the concentrations of the two substances. Their interactions would produce an ordered structure out of random chaos. There's an explanation of this process in the attached video. Go to timestamp 3:18

 

It is interesting that the stripes of an individual zebra are unique to that zebra, in the same way as your fingerprints are unique to you. This individuality is also the basis of eye pattern recognition used in security systems.

[facthunter]

Is it  white Horse with Black stripes or Vise versa? Nev

[red750]

I read a thing the other day where twin brothers had identical fingerprints and eye patterns.

[Litespeed]

As a identical twin- No, the eyes and prints are different.

[red750]

I didn't say you, there was a report.

[rgmwa]

3 hours ago, facthunter said:

Is it  white Horse with Black stripes or Vise versa? Nev

It's not a horse Nev. Please stick to the facts. 😊

Edited 21 hours ago by rgmwa

[facthunter]

It's as close to a horse as you're ever going to get. I was leading up to something but now it  won't go well. Nev

[nomadpete]

5 hours ago, Litespeed said:

As a identical twin- No, the eyes and prints are different.

Now that IS curious.

To think that identical twins with identical genes, can have some physical differences.

 

 

Edited 16 hours ago by nomadpete

[octave]

   

Identical twins (monozygotic twins) come from the same fertilised egg, so they start with almost the same DNA. 

• As the embryo splits and develops, mutations) can occur.

• Environmental factors in the womb — blood supply, position, nutrition — differ slightly.

• Over time, epigenetics (how genes are switched on/off) makes them even more different.

So they’re genetically similar but not 100% identical in every cell.

 

Monozygotic twins do not have identical fingerprints.

• Fingerprints form in the womb between about 10-24 weeks of pregnancy. 

• They’re influenced by random physical factors: pressure in the uterus, amniotic fluid movement, and how the fingers touch surrounding tissue.

• Even with the same DNA, those tiny differences lead to unique ridge patterns

Identical twins may have similar-looking fingerprints, but they are always distinct.

 

Identical twins can also differ in:

• Birthmarks

• Handedness (one left-handed, one right-handed)

• Susceptibility to certain diseases

• Personality traits

 

 

[old man emu]

12 hours ago, nomadpete said:

Now that IS curious.

To think that identical twins with identical genes, can have some physical differences.

Go back and watch the video for an explanation of how varience in a biometic feature is caused.  The differences are not influenced initially by genes. The genes allow the production of the causative chemical, but it is the random distribution of the chemical within the organ that causes the varience. That explanation does not deny that genes are responsible for the correct formation of a substance. What Turing's idea is that the genes allow the production of a substance, but the biometric feature is the result of the density of the substance as it diffuses through the organ. Imagine pouring 10 mls of black ink into a litre of clean water. Do that several times and you will never get the exact same distribution of concentration of ink in the water initially.

[red750]

The claim in the report may have been BS, but as they say, there can be an exception to every rule.

[old man emu]

 There are three living species of zebra: Grévy's zebra (Equus grevyi), the plains zebra (E. quagga), and the mountain zebra (E. zebra). Zebras share the genus Equus with horses and asses, the three groups being the only living members of the family Equidae. 

The skin of the zebra is black. The stripes are the result of differences in the concentration of melanin in the hairs - more melanin = black, less melanin = white. The differences in concentration can be explained by the concept of the Turing pattern.

https://en.wikipedia.org/wiki/Turing_pattern . Sometimes this effect goes wrong and a zebra has a coat without stripes. In those cases the coat looks brownish, but may have feint stripes or small spots.

 

Why does the zebra have stripes? Zebras suffer the scourge of flying, biting insects. Laboratory experiments have shown that alternating aras of black and white visually confuse these insects and they do not land on striped areas. Other experiments in which horses have been covered with striped horse rugs reduce the numbers of insects landing on the horse. (There's a commercial opening! Make horse rugs with a zebra pattern. I wonder if a checked or tartan pattern would work.)