Science

Cancer Happens

This one is going to disappoint some of you. What causes cancer? The answer is – life. Cancer happens; well, most of the time!

Primary reasons for cancer in humans are classified into three categories: environmental (E), hereditary (H), and mistakes during DNA replications (R).

Researchers at Johns Hopkins University evaluated cancer incidence in 69 countries and found correlations between cancer risks and these factors. Before going into details, please see the picture that I copied from Tomasetti’s paper (Tomasetti et al., Science. 2017 March 24; 355(6331): 1330–1334. doi:10.1126/science.aaf9011.).

First, a primer on what I meant by the replication factor, R. Approximately three mutations occur every time a stem cell divides. Most of these are inconsequential to us, but occasionally, they cause trouble. What is so special about stem cells? Stem cells are the body’s prime cells that give birth to cells with specialized functions – the blood cells, brain cells, heart muscle cells or bone cells.

Leading environmental factors known to cause cancer in humans include UV from sunlight, tobacco, soot, asbestos, carcinogenic chemicals, and ionising radiation.

Randomness, Again

These results also partly explain the observed stochastic nature of the disease. Remember, “my granny had cancer without smoking, and my uncle still smoking healthy”, all that stuff! Now you know the reasons for the deadly outcome are many – some you know already, some don’t, and perhaps never will.

Not an Either Or

Results from the study also point to the human tendency to rush to wrong conclusions, similar to a deductive fallacy. Environmental reasons are responsible for some cancer types, but it does not mean all cancers are due to Environment. To be precise, two in three are not! Does it mean you ignore environmental factors, smoke, eat tobacco, and give up sunscreen? Quite the opposite. One must continue avoiding exposure to carcinogens as they are the levers to manage those individual probabilities that are within your control, which eventually leads to a reduction in the combined chances of getting the disease (remember the AND rule of probability?). You thus avoided the disease, at least for a while!

The last takeaway of the study, which showed Pearson’s linear correlation of 0.804 between total stem cell divisions and lifetime cancer risk, leads to an unwanted prize for achieving higher life expectancies – the more you live, the more your chance of dying of cancer!

Science. 2015 January 2; 347(6217): PubMed Link

Science. 2017 March 24; 355(6331): PubMed Link

Stem Cells: Mayo Clinic

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Carbon Inequality

In an ideal world, our activities should result in about 2 tonnes of CO2 emissions per person per year, but in reality, it is 70 tonnes for the top 1% and less than 1 for the bottom 50%

The new Oxfam report starkly reminds us of the global disparity in consumption-based CO2 emissions and how the Paris Effect may impact the low-income 50%. The report presents a collection of data and future realisations, but I will not go through all of them.

In one of my previous posts, I commented about the present total CO2 emissions, around 47 billion tonnes in 2018 (Gt/yr). Oxfam report estimates the consumption-based emission to be about 35 Gt in 2015. The emission rate we need to target for 2030 is 18 GtCO2 to stay on course with the 1.5 oC target. Before we jump into the report details, take a stop for a quick recap of climate targets. 

The global mean temperature has now reached about 1 oC above the pre-industrial level; the world needs to keep its peak to about 1.5 oC to manage catastrophic climate change. In other words, the world can only emit a total of 420 – 580 Gt, as per the IPCC special report (SR 15), which is already three years old! So what remains with us to spend from today is less than 500 billion tonnes (carbon budget). There are different pathways to achieve the goal, and one of them is to cut the emissions by half by 2030 and net-zero emissions by 2050.

Back to the report: today’s total global consumption-based carbon emission is 35 GtCO2 – 17 from the top 10%, 15 from the middle 40% and a mere 3 from the bottom 50%! The per capita emissions are

21 tonnes per person for top 10%

5 tonnes per person for middle 40%

< 1 tonne per person for bottom 50%


Note that the top 10% is already trending at the total target of 2030 (18 GtCO2). The report estimates the expected reduction of the richest and the middle to be about 10%, which is much lower than the 90% and 57% required to reach parity (everyone shares the same per capita emissions).

The Paris Effect and its gaining traction in the developed world can lead to another moral failure of the equity principle. As we have seen in the distribution of COVID-19 vaccines, the morally agnostic twins, capitalism and technology, parented by populism and mistrust, will again fail to support the marginalised. Forcing emission cuts across the board will disproportionately impact the poor and widen the existing wealth and opportunity gaps. There must be additional climate finance, with a fair share from the top emitters, not just countries but also individuals beyond borders, to support the lower and middle-income groups to achieve the climate targets. Innovators, especially from the developing world, should also use this opportunity and focus more on inclusive low-carbon technologies.

IPCC Special Report

Oxfarm Report on Carbon Inequality

Paris Agreement

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SLC24A5 and the Great Human Divide

SLC24A5 is a gene. The gene finds a special place in human cultural discourse because it produces a protein critical to the production of melanin – the great-divider pigment of human skin.

What is an SNIP?

A single nucleotide polymorphism, or SNP, is a variation at a single position in a DNA sequence among individuals. If it occurs in more than 1% of a population, they are an SNP group. If the SNP occurs in a gene (resulting in what is known as alleles), it can have some consequences – rs1426654 is one of them, as we shall see.

A Quick Tour to the Basics

Imagine that the GENOME is a book. There are 23 chapters called CHROMOSOMES. Each chapter contains several thousands of stories, called GENES. Each story is made up of paragraphs, called EXONS, which are interrupted by advertisements called INTRONS. Each paragraph is made up of words called CODONS. Each word is written in letters called BASES. The words are written on long chains of sugar and phosphate called DNA!

– Matt Ridley in “Genome”
gene tree, tree of life, evolution-1490270.jpg

Allele and Us

As we have seen earlier, a gene has more than one allele if an SNP occurs within a gene. Our SLC24A5 gene also has alleles: the original allele that still dominates in the African and East Asian population (and contains the amino acid alanine), and the variant allele dominates in the Europen population (and contains threonine).

Why Me?

Why do ‘the originals’ have an alanine version, and what does it do? To answer the first part of the question, you should know how nature works. It is not that the originals have alanine, but only the alanine-containing humans survived the test of time in that location. The alanine allele triggers pigment production and defends the lower layers of the dermis from cancer-causing ultraviolet light, giving a small but significant additional life expectancy for people carrying this natural sunscreen.

The case with the sun-starved European side is quite the opposite: to fight Vitamin D deficiency, they must capture as much light (UV) as possible, and the pigment melanin is a potentially fatal blocker!

Does This Change Our Attitudes?

Unlikely. The notion that human complexion is only skin deep may be necessary but never a sufficient argument for people to stop distinguishing others based on colour (racism). Irrational as we are, humans will always keep inventing newer tricks to match their fancies and exercise their territorial powers. But this can, at least, refute one such stupid argument, and I will say I did not waste my page!

[1] SNP Definition: Nature

[2] Human Skin Color Gene: Scientific American

[3] SLC24A5: Science

[4] The Light Skin Allele of SLC24A5: Plos

[5] Skin Color for Indian Population: The Hindu

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Natural Selection

Natural selection does not mean nature selects something. It has no such powers (by the way, what is nature?)! Natural selection is merely the sum of all random activities resulting in an outcome. In other words, nature is what is imposed on it!

The first term is random (/ˈrændəm/; as per OALD: done, chosen, etc., without somebody deciding in advance what will happen or without any regular pattern ). Yes, the processes are random. 

The next up is activities; what are those? They are DNA replication followed by cell division (our life in one sentence). So, how much copying is happening in our bodies? Humans have about 30 trillion cells (30 followed by 12 zeros); on average, each one divides once a day, which is 30 trillion cell divisions per day. Even if you assume a tiny proportion of error during cell division, you could accumulate a few billion (called mutations) daily. 

In simple language, mutations are misspellings of DNA structure while copying. The body corrects most of it, but some may persist. Many of the mutations are neither harmful nor beneficial. So you get away. But, when it happens to the part of DNA that makes up a gene (gene variant), it becomes a serious affair.

Now, let’s come back to natural selection. Some rarer mutations lead to long-lasting consequences (maybe once in a few hundred generations) for an entire species. Say a skin colour change (I will explain that in another blog), a long nose or a pair of wings! 

Let’s take the story of tree frogs. Imagine two treefrogs in a society of treefrogs that got mutations that changed their colour – one got grey and the other green. If they lived in a dark wooded area, the accident enabled the grey variety to camouflage away from predators (snakes and birds). If you return after a few years, you will see the area is full of grey tree frogs. Now, change the scene to a green swamp. The genetic lottery is now with the green variant.  

The actions were random in both cases, but the outcome was specific.

When Charles Darwin (1809-1882) and Alfred Russel Wallace (1823-1913) came up with the term natural selection, little did they know his grandchildren would give it the opposite meaning.

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To Be or Not to Be: for a Decarbonised World

“That is the question.
Whether ’tis easier to ignore and suffer
The heat and cold of unpredictable future
Or to put life and money against the unwavering force,
And make a chance for my past to redeem?”

– a poor adaptation of Shakespeare’s Hamlet

What is decarbonisation?

Decarbonisation is the process of reducing human-made greenhouse gas (GHG) emissions. Based on scientific evidence, there are a bunch of gases in the atmosphere that can cause what is known as global warming. Out of these gases – carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) – CO2 accounts for more than two-thirds.

Why do we need to change?

Global warming, or the steady increase of mean global temperature, is well established and has been very dramatic since the early last century. GHG plays a pivotal role in warming and the associated changes in weather patterns (known as climate change). It is well-established by observations and through various climate models. The plot below shows the mean change in global temperature since 1880 (taken from NASA’s Global Climate Change page).

As per ClimateWatch, human activities are responsible for about 47 billion tonnes of CO2 equivalent in 2018, and 34 billion (73%) of it is from the energy sector. The remainder is predominantly agriculture and land usage.

Who can make a difference?

While the world needs to unite to manage GHG emissions, three sectors in the energy bucket hold the key to success. The top three sectors that account for approximately 80% of the energy consumers are industry (29% or 120 million TeraJoules), transportation (29%) and residential (21%) (based on 2019 data from the International Energy Agency (IEA)). Carbon-based fuels (oil, gas and coal) supply 80% of this energy.

How can we change?

There are a few options ready in the development funnel. The first one is using electricity as the primary vehicle for energy supply. And the electricity may come from renewables (wind, solar, hydro, geothermal), nuclear, and even carbon-based fuel with carbon capture and storage. The last option may work during transition, with a systematic plan to move away. Wherever storage is required, batteries and hydrogen (produced from water and electricity) come in handy.

What are the challenges? 

The first one that comes to mind is cost, especially for the industrial and transportation sectors. The fundamental driver for it to change is when the replacement’s total cost (capital and operation) is lower than the operating cost of the existing technology. Costs usually come down when there is production on a sufficient scale. However, here is a chicken and egg problem – higher costs prohibit the scale, and costs can not come down when the scales are low; it is the right time for the government to intervene through mandates and incentives.

Then comes infrastructure and affordability for electrification; both affect the transportation sector. The easy part is to produce electricity, followed by storage. Batteries help smaller vehicles but not the larger ones – the trucks, ships and aircraft. So, you require a different solution. The transformation of smaller vehicles also has its challenges. How will you provide incentives to a billion pieces of equipment spread all over the planet – be it charging points or simply the financial means to procure an electric vehicle?

The last sector is residential. You may think it was the easiest to change based on the public outcry to stop global warming. I will argue that it is the most difficult to change. First, like the case with cars, buildings are spread all over the world. Unlike automobiles, they are more expensive to change and even more difficult to convince that part of the problem is just in my backyard.

Further Reading

[1] Global trends temperature: NASA Page

[2] Energy Supply and Production: IEA

[3] GHG Emissions: ClimateWatch

[4] What three degrees of global warming look like: The Economist

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Three Books You Must Read

Read these books! I believe every human must read these. Three books by three eminent scholars who own different areas of expertise yet share their passion for unearthing our past and showing what made us the way we are today.

Guns, Germs, and Steel

American geographer and biologist Jared Diamond dives deeper into the sea of human history, mesmerising his readers with the pearls of wisdom to answer basic questions of human inequalities we see in the modern world.

Sapiens: A Brief History of Humankind

This Yuval Noah Harari masterpiece divides the human history of the last 70,000 years into three revolutions: the cognitive, the agricultural and the scientific. He then proves how the marginal and territorial hunter-gatherer, homo sapiens, learned the lessons of cooperation and became the master of the planet, scripting unparallel progress in the last few hundred years.

The Better Angels of Our Nature

Known for his witty and lucid writing style, Steven Pinker, a well-known speaker, linguist and cognitive psychologist, wields his literary sword against the believers of “those good old days”. To choose his own words from the book: “Cultural memory pacifies the past, leaving us with pale souvenirs whose bloody origins have been bleached away”.

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The First Post

Here we start. ‘Thoughtful Examinations’ is about life, knowledge, and happiness. It’s about numbers, rationality, and perspectives. I welcome you to the experience.

The Life of Chances

Probability, the mathematics of chances, is tightly woven into the fabric of life. Our existence started, evolved, and was nurtured by countless unlikely events – some are linked, some are not. We all studied the subject at school, the endless tossing of coins! Yet, it’s rarely applied in life. We will see the subject of probability and statistics as a recurring theme of my posts.

The Gates of Knowledge are Open

The gates have been crashed; the doors are open. The Tree of Knowledge is no longer hidden from your sight. The internet has made access to knowledge to each one of us. The democratization of knowledge is complete! Remember chances: yes, the chances that you reach your goals are better than ever before.

The Happiness Project

This page is for all who enjoy learning new things or getting new perspectives. This piece is for people confused by the volume of information out in public, finding it hard to separate the truth from the sea of junk. This one is a happiness project.

Life is about chances, knowledge, and happiness.

Once again, welcome to this journey. I offer whatever that I can to make it enjoyable. Remember: life is about chances, rationality, and decision-making.

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