How to make many sapient species on an alien planet without genetic engineering?
With the species of Damarian, as found on the list here, there are many different species, which all evolve at about roughly the same time.
Obviously, a huge problem about multiple species evolving simultaneously is that if they're all sapient, they can kill each other off in a deathmatch-esque war. However, I want most of them to have at least some technology, and for them to have survived long enough to accept one another.
So, without further ado, here's what Damarian's surface is like:
* Larger than Earth (1.5-ish Earth Diameter, roughly 4.5-ish Earth circumference, and thus (Most likely, following surface area calculation rules) several times Earth's surface area).
* Same percentage of land area and water area as Earth; 71% water (WAY more water than Earth, and also much more area, even with 29% land area)
* Most likely chillier, due to Damarian's orbit being roughly 384 days (19-ish days longer than Earth's orbit), but if it is, most likely the temperature differences would be minor, only noticeable at the (Much more distant) poles, and would be nearly indistinguishable at the equator.
* Orbits Aplha Centauri A, also known as Rigel Kentaurus, at almost the same distance as Earth does with the Sun, but more distant enough for an almost 19 day extension of the year (Hopefully, with Alpha Centauri A's bigger size and thus extra heat and light, habitability by humans is possible).
* Has 6 moons, which are NOT relevant for the question AT ALL; This question assumes the Damarian's orbit (And those of its moons) are stable and life has adapted to 5 moons and the tidal effects they all make. Plus, 3 of them are tiny ex-asteroids, and 2 of the other 3 are less than 1,000 km wide each. 701
The largest is about the same size as our own Moon.
* Four major landmasses: Gaundar (Mostly in the north of the planet, colder but longer and thinner); Tharizdun (Huge mass split nearly down the middle near the equator, resulting in a huge middle sea, with many hundreds of islands in the surrounding ocean; Sort looks like a fortune cookie that's been opened); Kehez (Comes from the south pole and goes up past the equator, getting within 2,000 miles of Tharizdun's southern edge, and gets fairly close to Gaundar on its northern edge); and Dendar (Southern temperate zone, close-ish to Kehez on the opposite side from Tharizdun). I'll be referring to the continents for the habitats.
Here is what Damarian's non-sapient life is like:
* VERY rich plant life (In the energy and nutrients easily available from the plant); fruit and nut eating herbivores only need to eat for about 30 minutes each day, leaf and fungus eaters only need 2-ish hours of feeding daily, and even grazers and grain eaters only need to eat about 4 hours a day, but typically spend most of their day eating anyway (Hey, why not?)
* This rich plant life means herbivores can sustain HUGE populations, which leads to much larger population counts of carnivores, which, along with Damarian's size, means that Damarian can hold much more biomass than Earth.
* The animals provide prey for the Stone Age peoples, who occasionally met. Being Stone Age people, each interaction was different: Some meetings ended with fight, others with trading.
So, using this question, I know that there are a few things the sapients need to keep themselves from killing each other: Different habitats (Easy, with Damarian being THAT big), but some way to interact often (I'm thinking they all can survive just fine in most climates, but usually live in two or three particular habitats), or have them have different niches or needs.
With all of my species in order of appearance, here's their habitats and general niches (During the Paleo- and Mesolithic Ages):
Volrortheans: Either chilly, Scandinavian-esque locales (Closer to the coast) on Gaundar or Kehez, or warm, Polynesian-like coasts on equatorial Kehez, and temperate grasslands of Kehez. They are typically megafauna hunters in smallish groups (4 to 12 adults, half that many youngsters).
Maravneans: Temperate plains and forest of Kehez, usually near rivers; Usually fish and hunt/gather.
Asterians: Hot deserts and temperate plains of equatorial Kehez, typically hunt and trap smaller critters and smaller members of megafauna species. 445