DECODING DNA

Which parent did you get most DNA from? 10 amazing facts about our genes

Image: Sangharsh Lohakare

Genetics can both fascinate and befuddle us with its complexity, but understanding its mechanisms just might be the key to deciphering the building blocks of our entire existence. From genes that are shared between different species to viruses that insert themselves into our DNA, here are 10 things you—likely—didn’t know about genetics and DNA.

Image: Ganapathy Kumar

We vastly underestimate the amount of DNA we carry around in our cells. If you were to unravel all the DNA molecules in your body and lay them end to end, they would stretch an astonishing 10 billion miles—enough to reach the moon and back over 40 thousand times! However, despite the vast amount of DNA in our bodies, if we were to gather and weigh all of it together, it would surprisingly amount to only around 8 ounces.

Image: Harshad Khandare

Surprisingly, humans share about 50% of their DNA with bananas! But this shouldn’t be too surprising given the fact that all life on Earth evolved from a single organism, roughly 3.5 billion years ago. Every living creature on our planet has the same type of DNA, undergoing almost identical processes in order to live and reproduce.

Image: Pedro Lastra

Certain species, like salamanders and starfish, possess remarkable regenerative abilities, allowing them to regrow lost limbs. Other species like axolotls or jellyfish can even go further, regenerating anything from parts of their brains to crucial internal organs, or even recovering from being cut in half! Understanding the genetic mechanisms behind this ability holds promise for regenerative medicine and even tissue engineering.

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Surprisingly, we inherit slightly more DNA from our mother’s side. While everyone receives 50% of DNA from each parent, a small portion of mitochondrial DNA, which is passed down exclusively from mother to child, contributes to this imbalance. Mitochondrial DNA also allows for tracing the ancient relationships of human populations, and for this reason, it is extensively studied in anthropology and evolutionary biology.

Image: Pietro Jeng

Scientists have already successfully stored digital data within DNA molecules, and many believe the technique has potential as a long-term storage solution. Its vast storage capacity and durability make it very attractive to store digital information, but the technology is still in development.

Image: George Prentzas

DNA is sort of a blueprint that determines most of our traits and characteristics, but it is far from having the last say on how particular traits or genes will express themselves. Environmental factors can modify gene expression without changing the underlying DNA sequence, potentially impacting health and development. This is the reason that even identical twins have noticeable differences, like unique fingerprints.

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Studies have shown that certain environmental factors experienced by parents, like exposure to stress or traumatic events, can leave chemical marks on DNA that are passed down to offspring. This phenomenon is called transgenerational epigenetic inheritance, and though it seems to contradict some of the tenets of Darwinian ideas, it is now widely accepted as one of the many mechanisms of genetic inheritance in most living organisms.

Image: Fusion Medical Animation

Rare genetic mutations can give natural immunity to certain diseases. In time, if these genes can be distributed sufficiently within a given population this can even lead to collective immunity. For example, there is a genetic mutation called CCR5-delta 32 that provides natural immunity to the Human Immunodeficiency Virus (HIV) by altering the structure of a specific protein these viruses use to infect cells. Studying these unique phenomena can be promising for developing cures and more effective treatments.

Image: Sangharsh Lohakare

A significant portion of the human genome consists of non-coding DNA, often referred to as "junk" DNA because it does not code for proteins. However, recent research suggests that this non-coding DNA plays important roles in gene regulation and genome stability, challenging the notion of it being just 'junk'.

Image: Belinda Fewings

Horizontal gene transfer is a very weird phenomenon where genetic material is transferred between completely different species, bypassing traditional vertical inheritance from parent to offspring. Although the mechanism behind this process is poorly understood, scientists believe that it played a significant role in the evolution of many organisms. In fact, certain types of viruses force this to happen in order to encode themselves into the DNA of their hosts and reproduce.

The mysteries of Scripture

Does everyone read the same Bible?

The Bible, the Tanakh, the Holy Scriptures, the Word of God: there are many names for this millennial text, but do they all refer to the same thing? Under the name ‘Bible’ —from the Greek biblia, ‘books’— we find different texts, some longer than others, connected to different faiths and traditions. What makes up the Bible? How does it vary from tradition to tradition? What was its original language? Keep on reading to find out the answer to these questions and other interesting facts about this sacred text.

While many people mistakenly refer to the Torah as the "Jewish Bible", it actually includes only the first five books of Moses—what, in Christian tradition, is sometimes called the Pentateuch. The complete collection of sacred Jewish texts is actually called Tanakh, an acronym of the sections included: Torah —the narrations and law written in the books of Moses—, Nevi’im —the Prophets—, and Ketuvim —writings of wisdom and poetic literature.

Are the Jewish Tanakh and the Christian Old Testament the same text? Not quite. Most of the text coincides, but is organized in a different way and translated from different sources. Additionally, books that are not part of the Jewish tradition—for example, Tobit or Judith—are not included in all Christian Bibles.

You might be surprised to learn that not all Christians read the same Bible. While the New Testament is the same, there are differences in what books are included in the Old Testament. Seven books—Tobit, Judith, Wisdom, Sirach, Baruch, and 1 & 2 Maccabees, plus some sections in Daniel and Esther— are considered part of the canon by Catholics and Orthodox traditions, but are not accepted by denominations of Protestant tradition.

Why are these books questioned? They were written at a later time than the rest of the Old Testament, around the 3rd century BCE, and were often only accessible through Greek translations. While Catholics and Orthodox have traditionally accepted them, the Protestant denominations do not, on account of their not being accepted as canonical by the Jewish tradition. However, these texts are often read as historical documents, even if they are not considered to be inspired by God.

The Bible was written across many centuries in different places, so the original text is not in a single language. The majority of the Tanakh and the Old Testament was originally written in Biblical Hebrew (which is different, although related, from Modern Hebrew), while some sections were written in Aramaic.

What about the New Testament? While most writers spoke Aramaic, the text is written in Koine Greek, a colloquial version of Greek used as a common tongue at the time. However, the text still includes words and phrases in Hebrew and Aramaic, such as amen, Abba, or hosanna.

As a text composed by many people across many centuries, the Bible was not penned in a single location, but across three different continents and several countries. The majority of the Tanakh/Old Testament was written in the ancient kingdoms of Israel and Judah, with some parts written during the Israelite exile in Babylon (modern-day Iraq). Additionally, some traditions believe that the books of Moses were written in modern-day Egypt.

What about the New Testament? Though closer in time, its sections were written in places all around the Mediterranean, mainly in ancient Judea, Greece, Macedonia, modern-day Turkey, and Rome.

The Bible is an anthology, written and compiled over several centuries and under different circumstances. As such, it includes a variety of known literary genres, such as historical narratives —for example, Genesis or Acts—, compendiums of law —Leviticus or Deuteronomy—, wisdom literature —Proverbs—, poetry —Psalms or Song of Solomon—, prophetic and apocalyptic texts —Isaiah, Jeremiah, or Revelations—, and letters —Romans or Corinthians.

In addition to all these genres, already established when the sections of the Bible were written, some books include the first recorded examples of a literary genre, such as the Gospels —a unique mix of narrative, biography, and theology—, or the Parables, which, unlike fables, convey complex moral and religious teachings alongside their interpretation.

All Bibles start in the same moment, the beginning of time, but not all Bibles follow the same chronology. The Tanakh narrates the story of the Israelites up until the construction of the Second Temple (6th century BCE), and the New Testament picks the story up around the years 5 to 1 BCE. What happened in the meantime? It depends on who you ask.

In the Protestant traditions, that gap is known as the "Silent Years", on account of the lack of inspired texts and prophets. In the Catholic and Orthodox traditions, the gap is shortened by Maccabees 1 and 2, which narrate the uprising against the Seleucid Empire in the 2nd Century BCE. There is, however, another biblical gap in the New Testament, known as the "Lost Years", that goes from the last mention of Jesus as a child —his visit to the Temple at 12 years old— to his baptism in the River Jordan at 30 years old.

If someone were to ask how many commandments are in the Bible, many would quickly respond that there are 10. However, not all traditions would accept this as a correct answer. The Jewish tradition recognizes 613 divine commandments or mitzvot. The first 10, listed twice in the Torah, are a list of fundamental moral and theological principles, while the remaining 603 regulate different aspects of life, such as society, rituals, ethics, or justice.

Do all Christian traditions follow the same commandments? Yes and no. The text of the Old Testament describes the ten commandments, but does not enumerate them, so each tradition has its own way of assigning numbers to each commandment, which can lead to confusion.

The biblical text is traditionally divided into books, which are divided into verses, but these divisions vary between the Tanakh and the Christian Bibles. The Tanakh contains 24 books divided into 3 sections—Torah, Nevi’im, and Ketuvim. The longest book is Tehillim or Psalms, while the shortest is the book of Obadiah.

In the Christian tradition, the longest book is Jeremiah, while the shortest book is John 3, with only 13 verses. The longest verse (in English) is Esther 8:9 with more than 70 words, while the shortest is John 11:35, with just two.

Have you ever wondered why there are many different depictions of Jesus around the world, even when they are most likely historically incorrect? The truth is, we can only guess what he looked like, based on the historical time and the geographical location, but we don’t have any physical description of him.

The four Gospels give us all sorts of information about Jesus, from his genealogy to his life, his family, his teachings, and his mission, but he is never described in terms of appearance. Even when different people talk about him, he is described based on his place of origin, his lineage, or his actions.

If you have ever read any part of the Bible, you might have noticed that many phrases are repeated. This is not a coincidence, but a deliberate literary device, intended to emphasize certain ideas and help to retain their message.

What is the most repeated phrase in the Bible? Both the Tanakh and the Christian Bibles coincide here, with the phrase "Do not fear" —and similar variants such as "Fear not" or "Be not afraid"— repeated more than 70 times in the Tanakh, and more than a hundred times in the Christian Bible.

Names carry a deep meaning in the Bible, often related to historical circumstances, spiritual characteristics, or prophetic messages. In fact, many passages involve the renaming of individuals to reflect a newfound mission or experience, such as God renaming Abram (‘exalted father’) as Abraham (‘father of a multitude’), or Jesus renaming Simon as Peter (in Aramaic, Kepha, "stone") to mean he would be the rock of early Christianity.

Among these names, one stands out due to its length and its ominous message. In the book of Isaiah, God instructs the prophet Isaiah to name his second child Mahershalalhashbaz, a name that means ‘swift are the spoils, speedy is the plunder’, and is interpreted as prophecising the upcoming invasion of Israel by the Assyrian empire. Fun fact: if this name rings a bell for you, it might be due to the actor Mahershala Ali, whose real name is Mahershalalhashbaz Gilmore.