All 9 essential amino acids can be found in a combination diet of rice and peas. It can also be found in Quinoa alone. It's one of the only plants that have these essentials in them.
Most people that swear by a meat-laden diet boast the benefits of eating meat; mainly that all 9 essential amino acids are in all meats. While this is true, it does not mean the healthiest diets contain meat portions exceeding 3 times a week. Fish are healthier than other meats, beef being one of the unhealthiest. The worst thing you can do is consume dairy.
The human body can subsist off of a lot of shit. That doesn't mean we're exercising our fullest potential, nor eating ourselves into cancer and other various diseases.