Ancient Viruses Are Probably Why Weed Has THC and CBD
THC and CBD are probably the result of freak genetic mutations millions of years ago,
scientists say. By Jordan Pearson 29.1.2018 “weed”
https://motherboard.vice.com/en_us/article/8xp593/an-ancient-virus-is-probably-why-weed-gets-you-high
Humans have been consuming cannabis for
millennia, but scientists are still largely in the
dark about the devil’s lettuce.
Thanks to new research, we now have a
potential answer to one enduring pot science
mystery:
Why does weed have the special chemical
compounds that affect humans, and other
plants don’t?
I speak, of course, of THC and CBD,
compounds known as cannabinoids that are
found in cannabis and have various effects on
humans.
THC is well-known as the main psychoactive
component in cannabis (i.e. it gets you high),
and CBD has recently become fashionable as
an ingredient in everything from drinks to
cosmetics.
According to a study published in the
November issue of Genome Research, these
two distinct compounds didn’t always exist in
the plant we now call cannabis.
According to the study, millions of years ago
ancient viruses may have colonised the plant's
genome and accelerated an evolutionary
process that changed its DNA and gave us
THC and CBD.
“The proteins [for THC and CBD] are
embedded in this huge mess of virus-like
sequences,” said Tim Hughes, a professor of
molecular genetics at the University of
Toronto and co-author of the study, over the
phone. “One thing that these sequences are
known for is facilitating the rearrangement of
the chromosome, and they’re actually a bit
dangerous in that way.”
According to Hughes, these viruses could
have accelerated an evolutionary process that
resulted in a single enzyme gene in cannabis
mutating into two, eventually giving us THC
and CBD. “It’s easy to imagine that, over a
long time scale, this process happened over
and over again in this part of the chromosome
where these two enzymes are,” he said.
This change led to ancient cannabis splitting
into chemically distinct types, and humans
then selected for plants with desired
characteristics such as high THC, according
to a press release for the study.
It’s hard to say what cannabis was like before
ancient viruses helped it develop the
properties we’re familiar with today, but
according to Hughes some of its closest
relatives are innocuous plants like mulberry
and hops.
The discovery that ancient viruses are
probably why people light up some cannabis
to unwind is a by-product of Hughes and his
colleagues’ research, which constitutes the
first full map of the cannabis genome to be
published academically.
In February, Colorado-based start-up Sunrise
Genetics unveiled a map of the cannabis
genome at a conference but didn’t publish a
paper, saying it would share the work publicly
“in less than a year.” Hughes and his
colleagues published a draft cannabis genome
in 2011, but it wasn’t detailed enough to
reveal the position of genes on the
chromosome.
Such maps are essential to improving our
impoverished understanding of the cannabis
plant. Hughes and his colleagues’ map is
already paying dividends beyond discovering