Genetics

What makes a species, what are genetics and why DNA matters more than you think

Have you ever wondered why lions and tigers can’t make cubs together in the wild—or why a mule (a horse-donkey mix) can’t have babies of its own? These questions lead us into one of the most fascinating areas of biology: genetics.

In this article, we explore what defines a species, how DNA makes each creature unique, and why even small genetic differences matter so much in nature.

What Makes a Species?

A species is usually defined as a group of living things that can breed with one another to produce healthy offspring that can also reproduce. Dogs and wolves? Same species group. Horses and donkeys? Different—because their offspring (mules) are usually sterile. That’s the key: reproductive success across generations.

But there are exceptions. Animals like ligers (lion + tiger) and zonkeys (zebra + donkey) are hybrids. They often look impressive, but most of them can’t reproduce, which is why they don’t create new species in the wild.

From https://tiger-universe.com/

Genetics and Reproduction

The reason many hybrids are infertile lies in genetics—the science of heredity. Every living thing has DNA inside its cells, which is organised into chromosomes. These chromosomes carry instructions for everything from eye colour to how a cell functions. Different species have different numbers and types of chromosomes. Humans have 46. Dogs have 78. If two animals don’t match up genetically, it becomes very difficult to create viable offspring.

Even small changes in genes can lead to big differences. It’s why tigers have stripes while lions don’t, and why two dogs of very different sizes can still have puppies together—they share compatible genetic blueprints.

To dig deeper into the science of heredity and chromosomes, check out this interactive DNA basics guide from Learn.Genetics.

How Genetics Drives Evolution

Over time, DNA can change through small errors or “mutations.” Some mutations are harmful, others helpful, and some have no effect at all. But when a helpful mutation gives an animal an advantage—stronger wings, better eyesight, better camouflage—that animal may survive longer and have more offspring. This is called natural selection.

When groups of the same species are separated—by mountains, rivers, or migration—they may adapt in different ways. Eventually, their genetics may change so much that they can no longer reproduce together. That’s how new species are born.

Photo by Sangharsh Lohakare on Unsplash

Genetics and the Future

Our understanding of genetics is now shaping the future. Scientists are using genetic editing tools like CRISPR to change DNA in plants, animals, and even medicine. In our earlier feature on CRISPR and the Future, we explored how these tools could solve diseases, boost food production, or bring back extinct species—along with the ethical questions that come with them.

At the same time, scientists continue to discover new species and study the genetic makeup of endangered animals to help protect biodiversity. Understanding genetics helps us track family trees, plan conservation strategies, and even decide how animals should be cared for in zoos and nature reserves.

To learn more about how species are defined and discovered, visit the University of California’s Understanding Evolution website.

Why Genetics Matters

From striped tigers to glowing jellyfish, from dodos to dinosaurs, the story of life is written in DNA. Genetics gives us the tools to understand how animals survive, why some disappear, and how humans can shape the future—for better or worse.

If your child is fascinated by science, animals, or how things work, genetics is one of the most exciting places to start.

📚 Further Reading

To explore more amazing science and stories from MiniMag, check out these related articles:

• 👉 CRISPR and the Future — Discover how gene editing is changing medicine, farming, and even conservation

• 👉 March 2025: Ancient Wonders and Future Discoveries — A magazine issue exploring how past and future ideas shape the world today