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From: RonO <rokimoto557@gmail.com>
Newsgroups: talk.origins
Subject: =?UTF-8?Q?Re=3A_Reverse_evolution_in_Gal=C3=A1pagos_tomato?=
Date: Thu, 26 Jun 2025 08:09:02 -0500
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On 6/25/2025 11:48 PM, Pro Plyd wrote:
> 
> https://phys.org/news/2025-06-tomatoes-galpagos-quietly-de-evolving.html
> 
> On the younger, black-rock islands of the
> Galápagos archipelago, wild-growing tomatoes
> are doing something peculiar. They're shedding
> millions of years of evolution, reverting to a
> more primitive genetic state that resurrects
> ancient chemical defenses.
> 
> These tomatoes, which descended from South
> American ancestors likely brought over by birds,
> have quietly started making a toxic molecular
> cocktail that hasn't been seen in millions of
> years, one that resembles compounds found in
> eggplant, not the modern tomato.
> 
> In a study published recently in Nature
> Communications, scientists at the University of
> California, Riverside, describe this unexpected
> development as a possible case of "reverse
> evolution," a term that tends to be controversial
> among evolutionary biologists.
> 
> That's because evolution isn't supposed to have
> a rewind button. It's generally viewed as a
> one-way march toward adaptation, not a circular
> path back to traits once lost. While organisms
> sometimes re-acquire features similar to those
> of their ancestors, doing so through the exact
> same genetic pathways is rare and difficult to
> prove.
> 
> However, reversal is what these tomato plants
> appear to be doing.
> ...
> 
> 
Solanaceae (tomatoes, potatoes, egg plant, deadly night shade) produce a 
toxin.  It is why peeling potatoes was so popular, and why people that 
that eat a lot of potatoes can exhibit some of the neurological effects 
of the toxin.  Cooking reduces the effectiveness of the toxin, but not a 
whole lot.  I was on a panel discussion on GMO agricultural products 
when I was a post doc at Michigan State, and we explained why things 
like putting an extra copy of growth hormone in a fish was not toxic or 
Round up resistant plants just had a naturally occurring enzyme put in 
them.  One member of the panel pointed out that natural breeding of crop 
plants had produced killer crops in the past.  Insect resistant celery 
and potatoes had been bred by just selecting the most insect resistant 
plants, and it turned out that they had selected for toxic levels of 
psoralen in celery that peeled the skin off the farm workers harvesting 
it in the first test crops, and the potatoes were found to have lethal 
levels of Solanaceae toxin.  The two examples were relevant because 
there are no regulations for testing naturally bred crops and both 
products almost made it out for public consumption.  The celery was 
abandoned because they could not harvest it.  A commercial product for 
the potatoes was being created and about to be marketed, but one of the 
researchers involved in the development of the product had kept working 
on trying to figure out why it was so insect resistant, and he found out 
that the potato had toxic levels of the toxin.  They could have poisoned 
millions because there are no food safety regulations for naturally 
occurring fruits and vegetables.  The public was worried about one 
additional possible antigen in soybeans, but they had no qualms about 
having Kiwi and Star fruit in the supermarkets with thousands of new 
potential antigens.

All that is happening with this tomato toxin is that one of the enzymes 
involved in making the toxin is reverting back to using and producing 
different stereo isomers of the toxin.  The ancestors had enzymes that 
produced one stereo isomer (had a specific physical structure), but the 
enzyme evolved to produce the other stereo isomer, so the toxin had a 
different shape.  There is no reason why this could not happen because 
the original enzyme had that activity.

It is just a reversion of the specific enzymatic activity.

We discussed chirality in a recent thread, and enzymes choose the 
chirality.  It isn't any miracle or supernatural phenomena.  Only a 
molecule of a specific physical structure can fit into a lot of 
enzymatic active sites, and stereo isomers have different physical 
shapes even though they have the same elemental composition.

Ron Okimoto