Welcome back to Nature League!
When most people think about DNA and the history of genetics, the names Watson and Crick usually
come to mind.
Or perhaps Dr. Rosalind Franklin, who provided the photo that helped the duo figure out the
structure of DNA.
But before the idea of DNA even existed, there were scientists who were studying the inheritance
of traits despite not knowing the molecule that makes it all happen.
One such scientist is Gregor Mendel, and he’s considered the father of modern genetics.
If you’ve heard his name, you might have learned that he was a monk messing around
with pea plants.
While this is true, there’s so much more to the story.
[CHEERY INTRO MUSIC]
Ah yes, the story of Gregor Mendel, the father of modern genetics.
Let’s take a look at this story...
Johann Gregor Mendel was born in 1822 in Heinzendorf, which was located in what is now the Czech Republic.
He was the middle child of two sisters, and his family were farmers.
He worked on the family farm when he was young, which likely fostered a love of nature, the
outdoors, and plants. Yes, we’re purposefully foreshadowing here, just roll with it.
Johann was smart... like, really smart.
So smart that people took notice, and urged him to leave the farm and go to secondary
school when he was 11.
Johann’s father wanted him to stay on the farm, cause, y’know...labor...and eventual
inheritance... BUT, his father also recognized the importance of education to escape the
hardships of peasant life.
Despite the financial strain, Johann attended two larger schools out of town and excelled,
graduating with honors in 1840 when he was 18 years old.
At 18, Mendel faced the understandable dilemma of figuring out what he wanted to do with his life.
College?
Gap year?
Eurotrip with buddies?
Fast food joint?
And by that I mean “work on family farm”?
Mendel decided to continue his studies, and enrolled at the Institute of Philosophy at Olmütz.
Throughout these years he struggled with both health and finances.
As for the latter, his little sis came through big time and lent him some money from her dowry.
Thanks, sis!
As for his health, it set him back in his studies, so he struggled to complete the program.
However, people were looking out for him and believed in his abilities.
One of his college professors, Friederick Franz, was a sort of scout for candidates
for the Augustinian monastery in Brünn.
Professor Franz recommended Mendel to these Augustinian monks, basically saying,
“Look, the kid might be poor, and kind of, well, sickly, but he’s really smart and you should
give him a chance.
Just do the right thing.”
At this point you might be thinking, “wait a second...if he joins a monastery, won’t
he just be monking around?
Where does education come in?”
Well, keep in mind that the monastery was a cultural center of that region during this
time, and it was complete with a massive library and places for scientific experiments.
The members of the monastery were composers, philosophers, and natural scientists, and
science education was actually emphasized for those in the order.
So it turns out the monastery was a pretty good fit for Johann Mendel.
His parents agreed, and in 1843 at the age of 21 he joined the Augustinian order at St.
Thomas’s Abbey in Brünn.
He took on the name Gregor, from Gregorius.
While there his roles included priest, botanist, abbot, chaplain, and eventually
a substitute teacher in 1849.
It turns out Mendel was really good at teaching.
He was like, “I’m really good at teaching.
Students like me, other teachers like me, I’m gonna do this” and he went for
a teaching certificate the next year.
Despite his best efforts, Mendel failed the certificate exam.
But one of the abbots saw potential in him and decided to ship him off to study at
the University of Vienna.
From 1851 to 1853, Mendel studied math, chemistry, and plant physiology.
He returned to the monastery in Brünn in 1853 at the age of 31 and was put in charge
of the gardens, which had been dedicated to agricultural experiments.
He was still interested in getting his teaching certificate, but failed the exam again in
1856, so at this point he was like,
“Dangit. Guess I’ll dedicate myself to this cool experimental work I’m doing on the side…”
The experimental work Mendel had been doing centered around hybridization, which is the
breeding of individuals from closely related species.
He was interested in how traits were inherited.
Keep in mind that at this time, the accepted theory of inheritance was “blending inheritance”.
Basically, people thought that the traits of parents blended together to create the
traits seen in offspring.
However, in the abbey’s garden, Mendel saw that pea plants weren’t following these
blending rules, so he “had to investigate what was going on”.
From 1856 to 1863, he crossed tens of thousands of pea plants with different physical characteristics
to track these traits throughout several generations.
The physical characteristics of pea plants he worked with were plant height, pod shape,
pod color, seed shape, seed color, flower position, and flower color.
By crossing plants with combinations of these traits, Mendel noticed certain mathematical
patterns in the offspring.
For example, when a plant with yellow seeds was bred with a plant with green seeds, all
of the offspring were yellow.
However, when he bred the next generation of those plants, only 75% of the offspring
had yellow seeds, and 25% had green.
During this work, he made four very important observations:
Number 1: “Traits have multiple forms.
For example, pea plants can be tall or short.”
Number 2: “Offspring get character traits from their parents through some kind of factor they inherit.
I don’t know what the factor is, but it’s definitely happening.”
Number 3: “In organisms with two parents, it seems like one factor comes from each parent through
sex cells.”
Number 4: “Offspring outwardly express only one of the two factors they inherit from their parents.
Let’s say the factor that gets physically expressed is dominant,
and the other factor is recessive.”
But Mendel wasn’t done yet.
He also noticed that when parents with differences in two traits were crossed, the offspring
would have all possible physical combinations.
For example, if one parents was tall with green seeds, and the other parent was short
with yellow seeds, the offspring were all four physical combinations.
Since the offspring had combinations that were different from the parents, Mendel concluded
that these traits were inherited independently of one another.
Basically he figured, “there’s no relationship between height and seed color.”
This observation was a big deal, and is still taught and referred to
as the Law of Independent Assortment.
Mendel was pretty pumped about his findings, and he presented them at meetings in 1865.
He published the findings the next year, reporting that some invisible “factors” were providing
visible traits in a way that was predictable.
We now know that these invisible factors are genes, but DNA wasn’t figured out until
after Mendel had died.
Most tales from this time that reference his work indicate that people sort of missed the point.
Scientists misunderstood his findings and didn’t recognize the significance at the time.
He spent his later years too busy to focus on his experimental work and wrapped up in
tax drama.
Mendel died in 1884 at the age of 61.
But was this the end of Mendel?
Not quite.
Though his ideas were largely unknown when he died, they were rediscovered some 15 years later.
In 1900, three European biologists did their own experiments and came to the same conclusions
as Mendel.
Thus, the age of genetics was born, and in combination with Darwin’s theory of natural selection
and works by other scientists, the modern synthesis of evolutionary biology soon arrived.
Although we’ve learned a lot since the time of Johann Gregor Mendel, his work still serves
as a foundation for genetics research in the 21st century.
His theories have fallen in and out of favor over time as new discoveries unfold, but his
research is fundamental to understanding the field of genetics.
Thus, he is considered the “father of modern genetics”.
Thanks for joining us on this historical episode of Nature League.
We’ve come a long way in certain fields of study, but it’s always good to learn
about how we got here.
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