17.5 C
Niagara Falls
Tuesday, May 28, 2024
Dr. Brown: Will humans soon take evolution into our own hands?
Firefly image.

In week three of this five-part series on the Middle Land, we examined how life began and evolved and the life cycle of stars, including the creation of heavier elements in the cores and subsequent implosion and outward blast of the death of stars in supernovae. 

But for the most part, humans live in the present — preoccupied with the events and demands of the day, less often with what’s coming, and totally oblivious to the marvels of life and the cosmos.

True, we sometimes fret about the future and ruminate about the past but for most of our time, we’re preoccupied, like other mammalian species, with the here and now.

On a much longer time scale, we behave as if our species is fated to continue much as it has in the past and that even if, as individuals, we may not be immortal, our species is. 

Here, the archeological, and more recently, genetic records, suggest a very different future for our species.

Past records strongly suggest that modern humans were preceded by a complex array of closely related ancestors, whose anatomical and cognitive traits evolved in response to changing environmental pressures at different times for the last six to five million years — of which but one, sapiens, remains. 

Looking forward, it’s hard for this writer to think that our species will last any longer than our ancestors, given that evolution based on natural selection continues to mould our species in response to continuing environmental pressures, which, according to some experts, may be speeding up. 

Looking beyond natural selection, the recent introduction of gene editing technologies such as CRISPR and now improved versions, which allow investigators to edit multiple genes at a time, promise to shake up evolution.

The technology to fix single gene disorders using gene editing became a reality recently with successes with thalassemia and sickle cell anemia — whatever the angst of some over the potential risks posed by the technology. 

Beyond efforts to fix single mutant genetic diseases is the prospect of changing human traits such as height, physique and, most alarming for many, genetically upgrading cognition.

Cognition and behaviour are complex and probably depend on the interplay of hundreds if not thousands of genes and much past the first few months of life, family, cultural and environmental influences.

That very complexity poses a hurdle, if not an insurmountable one, to gene editing in the future. 

Working out which genes play key roles in cognition and behaviour is the first hurdle.

The second hurdle would be to edit the genome to incorporate those genes in their right places to create desired cognitive and behavioural traits.

Present-day gene editing works with single genes but modifying or inserting hundreds of genes poses a huge challenge.

Why? Because some genes have more than one function and inserting those genes may well be associated with unanticipated and undesirable consequences.

Even so, gene editing has moved beyond fixing single genes to possibly changing multiple genes, giving me reason to think that the ability to change behavioural performance traits is coming — it’s only a matter of time. 

Adding to the complexity of cognition and behaviour, the brain’s development is powerfully influenced by opportunity, culture and education, especially early in life.

The underlying mechanisms may involve epigenetic changes to the genome such as methylation of bases, alterations to which may turn some genes on and others off during development and possibly later in life.

Doing so could alter behaviour and cognition without changing the base sequence.

Recent evidence suggests that some epigenetic changes can be passed along from generation to generation.

If so, we can now add epigenetic influences to changes in the genome as possible avenues for changing traits.

It won’t be easy to boost cognitive powers expressed as social intelligence, learning, reasoning, mathematics, imagination, creativity, language and artistic talents to name a few interrelated and dependent cognitive traits. 

But given the trajectory of brain research and genetics these days, the barriers to enhancing complex cognitive powers will likely be surmounted in this century or at least, the next.

This would put humans firmly in charge of their own evolution and that of all other creatures from single-cell organisms to complex highly developed intelligent animals.

This represents the first major challenge to evolution by natural selection since life began 3.8 billion years ago

Next: In the finale of this series, we tackle the question of whether our species will survive and, if so, will we, as all our predecessor species did, morph into other species cognitively and behaviorally, or come to an end — the last of the line and then gone.

Dr. William Brown is a professor of neurology at McMaster University and co-founder of the Infohealth series at the Niagara-on-the-Lake Public Library.

Subscribe to our mailing list