Seaweed is much more than that gross stuff that gets stuck on your leg at the beach or that green thing in your sushi. This unlikely plant might have provided a helpful step in our evolutionary origins millions of years ago, according to a new study.

Scientists from the University of Southern Denmark have carried out research that indicates a variety of seaweed could have provided the vital nutrients needed to develop a complex brain millions of years ago, eventually pushing us from primitive hominoid ancestor to modern human.

Seaweed is packed with essential nutrients for brain development in present-day humans, namely taurine, magnesium, zinc, vitamin B12, iodine, and poly-unsaturated fatty-acids. Many of these nutrients have been linked with central nervous system development and can help improve attributes such as memory, concentration, language, and increased blood flow in the brain, according to the researchers.

"Nutrients needed for this transition from a primitive ancestor to modern Homo sapiens were (and still are) available in seaweeds," study author Professor Ole G Mouritsen said in a statement. "Seaweeds could be found and harvested in abundance on shores, and for a foraging lifestyle, a rich coastal environment would be a significant source of a consistent supply of these nutrients."

The human lineage diverged from our closest living relatives, chimpanzees, around 5 to 7 million years ago. Around 2 to 2.5 million years ago, when early human ancestors ruled the land, there was environmental upheaval and a massive expansion of the African savannahs. The researchers argue that this might have forced hominoids to coasts to forage for food like fish, crustaceans, snails, bird eggs, and seaweeds.

"Foraging over longer distances for food would have contributed to bipedalism and a different body stature as increasingly larger ranges had to be traversed, and in the case of our primitive ancestors, this would undoubtedly lead to significant changes in diet," the authors write.

Once they reached the coasts, seaweed required less hunting or foraging skills compared to other foods, while also being delicious and highly nutritious.

"Seaweeds can be found all across the intertidal zone from the high water mark to the subtidal regions and they could be readily and repeatedly harvested for food by all family members, including women and children," the authors state.

They argue that it seems quite the coincidence that hominids then began to eat this super-nutritious brain food around about the same time they were embarking on the long journey of slow but steady intellectual development. The researchers are merely speculating on this, but it's a fascinating idea nonetheless. 

The full study can be found in the Journal of Applied Phycology.