[ry454]

Here's a possible explanation that I'd seen somewhere. Up until very recently, humans had had weak ability to think, especially abstract thoughts, and the phrase common today "just think about it", would be meaningless just a few centuries ago. Perhaps the concept of depth in those times would be similar in complexity to 4-dimensional structures today.

[imtringued]

That's completely wrong. Humans were just as smart 3000 years ago as they were today. The difference between today and back then is that people were much poorer and didnt receive an education. Their jobs were farming which didnt require things we consider essential like reading or writing which meant they stay unchallenged for their entire life. When you look at the rich elite or rich cities in the past then you see how small the difference between us and the people 3000 years ago is. They were just as smart but there were fewer of them. Nowadays everyone is educated and "rich".

You can still find people who are just as "unchallenged" as a medieval peasant today. Look in rural places of countries like china.

[GuB-42]

Another big factor, I think is communication. Today, discoveries spread almost instantly, all over the world. But back then you had hard to copy manuscript and people had to meet in person using slow and dangerous transportation.

So I think ancient discoverers wasted a lot of time rediscovering things.

[cft]

This is a nice theory, but what is the proof? Were people just as smart 30,000 years ago? What about 300,000 or 3 million years ago? How do you set the time scale? When was the boundary when people became smart?

[tsimionescu]

We don't know exact dates of course, but looking at the works of mathematics and philosophy that have survived, we know for sure that humans were capable of abstract thought at least as far back as 4-5000 years ago (for example, during the construction of the Great Pyramid of Giza), and very likely even 12-13000 years ago (during the construction of the megaliths at Gobekli Tepe, for example). Furthermore, we can assume that some time must have passed between the first threads of abstract thought and any achievements due to it that would stand the test of time, though I don't think we can put any hard estimates on this time.

[PeterisP]

We can look at the genetic changes and timeframe of them, and how certain mutations have spread - novel changes in our species are not that frequent on the historical timescale. People 3000 years ago are the same with respect to their biology, so they have to be "just as smart"; hominids 300,000 years ago are different in some aspects so for them we can't really know how "smart" they were, perhaps they were as smart, perhaps they were not.

[roomey]

Plato? Socrates? Pythagoras?

I was an artist for a while. It wasn't that artists couldn't depict depth. Fashion, religious instructon, and to a lesser extent materials, is what decided which paintings and frescoes lasted the test of time.

[PeCaN]

Humans were actually incapable of abstract thought until hacker news invented it.

[lenkite]

There are mathematics texts from 8th century BCE: https://en.wikipedia.org/wiki/Baudhayana_sutras