- [Narrator] Where did the cannabis we know today come from?
Its wild beginnings remain unknown.
But by looking at the plant's genes,
we can identify its closest living relative.
- Hops, which we use for beer,
is the closest existing species to cannabis.
- [Narrator] Plant geneticists estimate
that some 28 million years ago,
cannabis and hops plants diverged.
Today, cannabis contains special compounds
called cannabinoids, molecules like THC,
which can make someone high, and CBD.
- And we know that the cannabinoids appeared in cannabis,
but hops does not have them.
- [Narrator] Which means that cannabinoids appeared
after cannabis split from hops.
We're not sure if or how the evolution
of these compounds benefited cannabis,
but they may have protected the plant against UV light,
or kept it from being eaten.
Whatever the reason, humans took note
and started growing cannabis for different uses.
- We do know that there's many different ancient cultures
that have been using it for a long time.
The Chinese, for example, the Greeks and the Romans.
The Indians have used it for medicinal purposes,
but also for industrial purposes, rope and canvases.
They would use it for paper.
But also for medicinal purposes and for rituals.
- [Narrator] By studying the genes
of over 100 different varieties of cannabis,
geneticists estimate that around 12,000 years ago,
the wild cannabis plant broke into two lineages,
one of which was likely bred for crops.
And this crop lineage split again about 4,000 years ago
into two more groups, hemp plants, selected for fiber,
food and textiles, and a second group used
for their psychoactive properties.
These two characteristics, strong fibers
and psychoactive effects are largely due to domestication
and the process of artificial selection,
which is when certain traits are chosen by people
and reinforced through breeding.
- So let's say they wanted to have a high THC level
in the plants, so they were breeding for high THC,
or they wanted certain colors.
So that's how they were selecting for the plants
that we currently have in the market
and that have all those names available.
- [Narrator] This kind of selective breeding,
which started thousands of years ago, continues today.
Both the hemp and psychoactive varieties
belong to a single species, cannabis sativa.
- So far we think it's one species
that has a lot of variations, both physically,
so phenotypically and genomically, so in the DNA.
- [Narrator] Today, federal law draws a distinction
between the two.
The difference lies in their THC levels.
- The legal definition of hemp is anything
that produces less than 0.3% THC.
And we found that those groupings from the industry
really do not mean much.
And we think that it's more related to how people feel
when they consume the different products.
- [Narrator] Hemp and the psychoactive varieties
may have some distinct physical features
that set them apart.
Hemp is taller, fibrous and is less bushy
than the psychoactive plant.
In recent years, cannabis growers have artificially selected
and bred plants with even higher amounts of THC.
As a result, today's cannabis may be far more potent
than its ancestor, or even the cannabis
of a couple decades ago.
And now scientists have managed
to produce both THC and CBD without the plant at all
by genetically engineering bacteria and yeast.
- I am wondering how will governments and legal institutions
look at this innovative aspect that we do have in science
and that is actually growing big in the industry.
- [Narrator] Completely replacing the cannabis plant though
is unlikely.
Humans have been cultivating it for thousands of years,
and a relationship like that is hard to break.
(light upbeat music)