I mean, we start up like an every other race, we have a decent planet, good stats, some billions of population.
But then we hopelessly lag behind. Even in comparison with a normal growth rate race we're like riding a bicycle in a car race.
While high fertility races colonies turn into a bustling industry or science hub just in a half of century, ours are more like a backwater hyperjump relay, with some cabins for personnel and their families and a fast-food stand or two.
So, we adapt.
Then we adapt others.
What is the point in trying to breed ourselves, when we can turn others into us?
In this game I'm trying to win withour building any colonies. No colonizers, no relays, nothing of the sort.
I use a custom race based on Lezgoon with telepathic switched to parasitic and some minor changes in traits and techs.
Oh, and they're from a desert planet San in a system Francisco.
It is an average sized galaxy, 12 anomalies, very hard difficulty setting.
Instead of usual going post-industrial (I guess, there's some galactic China in-game) I've decided to split my workforce between industry and science this time:

The reason is simple, I won't get enough science points from my 4.5b anyway, so I'd better save money and build up.
I build scouts both for exploration and combat. Here's the design that will rule the galaxy:

It comes at a hefty price, though, ~0.5bc and 15 turns to build.
However, as the practice shows, it's worth it. Antimatter torpedoes (thanks, Lezgoon ancestry) pack missile-like alpha damage, combined with the guns projectile speed (infinite, actually).
So, I spend about 70 turns lazily exploring. A Barbeck pod here, a crystalline resource there.
I upgraded some logistics and targetting, built 5-6 scouts and a starbase (in order to automatically refit the scouts for logistics).
Also, I've built a fairly standard transport with 35k troops by the way.
And then I hit the motherlode:

Two civilizations, two fine, juicy civilizations!
Which one to ripe first?
I looked at the chart and got confused about the number of Gargal colonies.
They had two but I somehow decided they had four.
As I was in no shape (no construction techs except for androids and gravity generator meant I was a very soft target for invasion) for a long war, I decided to go after Humans.
I bought two additional scouts, ordered another transpart and went for it.
Funny thing is that any aspiring body snatcher needs to go after the most populated colony of the victim race.
On the early stages antimatter torps rip through any reasonable defences, if you have initiative (i.e., antimatter drive).
But with the big population antimatter torps allow somwhow less collateral damage. And with the target population of ~50m you'll just glass the planet and won't gain anything.
So I mercilessly shred the planet (I spend two turns on it) and I was satisfied with the results:

Even with such handicap, my invasion force got much beating.
But, anyway, troops just grow on dropships, right?
Gargals went belly up the same way.
My second transport joined in and victory was even easier.
However, I slipped with their second colony.
The ratio between my soldiers and Gargals needed to be at least 5:1 for me to win, and I accidentally the whole colony.
My bad.
Here's how my population looks on chart:

Notice the sharp drops, that's the inevitable mass famine in an assimilated colony.
If I wasn't parasitic, I would have lost even more assets.
Well, that's it for now.
I've just made contact with Kuntari.
I believe, they think I'm a good guy.