Why did it take so long to discover Mendelian inheritance?

[Lorizael]

This is a discovery that doesn't seem to require a lot of technology, mathematics (just a little probability), or knowledge of underlying physical principles, yet it took thousands(?) of years of cultivating plants and animals to figure out these rules. And we'd clearly been consciously selecting for particular traits in our plants and animals for a good chunk of that time, so it's not like no one was paying attention. Yes, most traits can't be worked out with a simple Punnett square, but there are still plenty of paradigmatic examples in nature. So why is this discovery only 150 years old?

Curious to hear people's thoughts. Correct answer in spoiler tags for those who want to know.

Spoiler:

Mendel wasn't born until 1822.

(NB: I'm not arguing that Mendel's discovery wasn't impressive; it clearly took a great deal of patience, effort, insight, and possibly some fudging of numbers.)

[Aeson]

His birth was the first time in history where both the parents had the pea-brain recessive trait?

[KrazyHorse]

Rareness of single gene phenotypes?

[N35t0r]

Availability of enough free time?

[Lorizael]

Rareness of single gene phenotypes?

I don't know. Relatively rare, yes, but certainly not impossible to find.

http://omia.angis.org.au/home/

Online Mendelian Inheritance in Animals (OMIA) is a catalogue/compendium of inherited disorders, other (single-locus) traits, and genes in 224 animal species (other than human and mouse and rats, which have their own resources)...

The list is mostly domesticated animals, and things like coat color are pretty common.

[Ben Kenobi]

This is a really good question.

Mendel's inspiration was to try working with plants and not animals. His teachers had worked with animals and not found these laws, because the animals that they worked with did not behave in such a predictable fashion - in having single phenotypic characteristics.

Why didn't it happen earlier? Aristotle's natural philosophy did not correctly identify substantial difference from accidental morphological differences. Goethe's Metamorphosis of Plants had to happen before any of the work pertaining Mendel's could proceed.

After Goethe's work - the concept that there were substantial characteristics that could be passed down to plants - as a hypothesis became tenable. The problem was how to prove them. Mendel managed to find a successful trait that could be observed that did pertain to substantial differences between two types of peas.

[dannubis]

Because he hid it under a rock.

[KrazyHorse]

I don't know. Relatively rare, yes, but certainly not impossible to find.

http://omia.angis.org.au/home/

Online Mendelian Inheritance in Animals (OMIA) is a catalogue/compendium of inherited disorders, other (single-locus) traits, and genes in 224 animal species (other than human and mouse and rats, which have their own resources)...

The list is mostly domesticated animals, and things like coat color are pretty common.

Yes, but now you've got experiments that give confounding results (plus even with a single gene phenotypes you have the issue of initial unobservabl purity of breed, so only a carefully chosen starting population will actually yield the familiar result)

Not all that surprising to me it took until when it did.

[Proteus_MST]

Considering that humans practically used crossbreeding/hybridization for thousands of years
(like with grains and dogs) it is definitely interesting that it took them so long to formalize the laws behind this

[giblets]

Lots of discoveries seem obvious in hindsight.

[The Mad Monk]

Because he hid it under a rock.

Hah?

[Lorizael]

Yes, but now you've got experiments that give confounding results (plus even with a single gene phenotypes you have the issue of initial unobservabl purity of breed, so only a carefully chosen starting population will actually yield the familiar result)

Not all that surprising to me it took until when it did.

If you are arguing that relative rarity is sufficient, then it also seems you're suggesting that humans probably failed to make the discovery before Mendel. So, then, what is the probability of making this discovery? According to this site, from pre-history to 1850, there were ~94 billion people. If only 1 in a million (ass pull) were smart enough and had the opportunity to make the discovery (and they grew like the population), then failed discovery until 1850 is likely (p > 0.5) only if the chance of discovery per smart person with opportunity is roughly 10^-5 (math: 1 - .5^1/94000). Hm. I have no idea how to characterize the chance of discovery, of course.

[Lorizael]

Lots of discoveries seem obvious in hindsight.

I am specifically not arguing that the discovery was obvious, just that it's a discovery which doesn't require modern science/technology/math, so why was it not discovered until we had those things (more or less)?

[onodera]

Not enough Mendelian traits around. It was his luck that he managed to pick those that traits that actually were Mendelian.

[Dinner]

My guess is no one else bothered to look and study the topic systematically. To be sure the Austrian monk had lots of time and professional training plus scientific discovery was all the rage back then.