How do you live? I can only survive on 75% carbs.

I discourage anyone from going low carb.  I encourage everyone to avoid refined carbs.  Yes, it's good to avoid flour, refined sugars, etc.  No, it's a terrible idea to avoid beans, broccoli, fruit, etc.  I probably fall a little shy of 75% because I eat a lot of nuts and seeds which are heavy on healthy fats (including high amounts of omega 3s in the chia and flax seed that I add to my fruit salads), but I'm probably in the 60-70% carbohydrate range in my diet.  I haven't updated Cronometer.com for a while, probably worth checking again.

What are the poisons then? Starch and saccharose? And why are those poisons?

It was on the rise in China, and may still be, but the Chinese government has been working with celebrities (including a recent campaign with James Cameron and Arnold Schwarzenegger) to encourage their citizens to start eating less meat.  Here's the video (starring Schwarenegger) that resulted from that collaboration:  https://www.youtube.com/watch?v=c3q-7ish6vk

It's refined carbs.  It's taking the carbs out of their natural state and turning them into a highly refined product.  Eating a potato is healthy (only made potentially unhealthy by what you put on it).  Eating a potato chip is unhealthy.  They're both a starch, but one is a natural and unrefined starch, the other is a highly refined product that taxes the body.

Here's another example:  Eating fruit is incredibly good, drinking fruit juice is not.  The fibre and protein in whole fruit slows its absorption and lets the body get the sugar and nutrition naturally; fruit juice is a refined product that typically contains no fibre and hits the body way too fast and hard and taxes the body as it absorbs it.

If you're eating a wide variety of whole plant foods, you almost can't do it wrong.  If you're eating highly refined products, you almost can't do it right.

Ummmm....   got a link for that?  Because I can cite a tonne of sources that say otherwise, including analysis of mummified human hair and rehydration of fossilized human stool that doesn't leave much to the imagination about what people ate in times gone by.  All the evidence I've seen suggests your statement is categorically false.  It is true that meat consumption has dropped in a few countries over the last generation or so, which is positive, but it's nowhere near the 80-90% drop you suggest.  I can't see any way in which your statement could be correct, unless you're talking an incredibly short span of time, and an incredibly tiny geographic area that bucked the global trend.

EDIT:  I see in a follow-up post you said prehistory.  Now we know you're incorrect.  It's a myth that hunter-gatherers mostly hunted.  Most hunter-gatherer populations mostly gathered and had diets rich in plant foods.  This isn't a matter of debate, you can look at mummified hair and analyze it to get a sense of their diet.  Ditto when you find fossilized human stool.  A whole food vegan diet is more paleo than the so-called "paleo diet".

Not sure if serious...

Many fish have nearly as much saturated fat and cholesterol as beef so... yeah, fish is meat and similarly bad to the other meats that humans eat when it comes to being associated with health problems.  And I say that as a former pescetarian.

The problem with that is that sometimes the first sign of a health problem is death.  Look at Kevin Smith (who's now considering going vegan in the wake of his massive heart attack).  It's pretty difficult to course-correct if the first symptom is death.

Other times the first symptom is cancer.  Cholo-rectal cancers are amongst the cancers tightly correlated to eating animal products, but there are many more.

Dietary changes do a better job of preventing disease than they do curing disease.

Serious question(s) if you are indeed 44 have you not noticed that dietary "science" is a constantly changing animal? What is good for you one year "causes cancer and is bad m'kay" 5 years later only to once again be good for you three years after that.

Also how common is fossilized human stool? A search for coprolite returned mostly things of this nature:

https://news.nationalgeographic.com/news/2014/06/140625-neanderthal-poop-diet-ancient-science-archaeology/

not sure how this relates to your statement "A whole food vegan diet is more paleo than the so-called "paleo diet"."

Also, going against my link, is a single recovered stool sample really a good way to come to a conclusion about what "people" let alone A person ate regularly?

A single turd is but a snaphot of part of my diet and does not describe in whole what i normally eat. Yesterday's salad is today's turd like Monday's steak dinner was the turd before that.

Not trying to be an ass as I am not well versed in this area so feel free to include links to further my knowledge.

Vegans and vegetarians grew from 2.6% of the population in Israel in 2010, to 13% in 2014 (and appears to have grown even more since then).  (source: https://www.jta.org/2014/10/15/life-religion/israelis-growing-hungry-for-vegan-diet)

I'm not sure where you are, but veganism is estimated to have grown 500% in the U.S. between 2014 and 2017.  (source: https://www.riseofthevegan.com/blog/veganism-has-increased-500-since-2014-in-the-us)

You asked for where the change is coming from, and those are a couple of examples.  :)