Did you know?
FACT: Dogs have genes and DNA, just like the rest of us.
Like their human carers, the domestic dog’s genetic material (their genes) is stored as chromosomes. When a cell divides, it packages its DNA into these structures. All domestic dogs, no matter their size, shape or colour, carry their genetic materials on a total of 78 chromosomes. These are found in pairs, with each pair being made up of one chromosome from each parent. One pair of these chromosomes determine a dog’s sex; just like humans, X and Y chromosomes exist, with dogs being XY and bitches XX.
FACT: Dog chromosomes were first described by scientists in 1928.
A gene is a functional unit on a chromosome that directs an organism’s cells to perform a particular function e.g. your red blood cells carry oxygen around your body using a protein called haemoglobin. This protein is made from a master set of genetic instructions in two genes that sit on different chromosomes. The genetic instructions are written in a code of A, C, G and T letters.
FACT: Dogs’ best friend (humans) have 46 chromosomes and their famous enemy (cats) have 38.
Despite the difference in numbers, dogs, cats and humans have pretty much the same overall amount of DNA in each cell.
Organisms with the largest number of chromosomes: ferns often have over 100 chromosomes, with some having over 1000.
Organisms with the smallest number of chromosomes: ants, spiders and flies, many of which have fewer than 10 chromosomes. Fruitflies have 8, mosquitos have 6 and some ants as few as 2 chromosomes.
Why so many shapes, sizes and colours of dogs?
Much of the variation we see between any member of the same species (dogs, cats, humans) arises from small changes to their genetic material, DNA. These changes occur by a process called mutation and without it; the diversity of life we see on Earth would not exist. Mutation in DNA creates the variability on which evolution works.
For dogs, interesting and useful features are identified and, because they are determined genetically, they can be bred by selective breeding (i.e. choosing animals with features you want and breeding them to create new offspring with those features). We have bred dogs with regard to developing better functional capabilities (running, hunting, digging, burrowing, carrying, etc.) or looks (colour, size, shape, skin (wrinkliness), hair (texture, hairlessness), head size and shape).
What are the origins of dogs?
Domestic dogs go back at least 10-15,000 years. Most modern domestic dogs are actually derived from this larger pool of domestic dogs that arose from wolves. We can’t actually say for certain exactly when this happened, or how many times it might have occurred.
Why don’t we know for sure? Scientists can estimate when dogs and wolves first became distinct lines by comparing the genome DNA sequences of today's living animals. We know how many DNA differences there are between dogs and wolves today, so working backwards, you can (in theory) work out when they were last the same species. However, scientists still disagree with the rate of mutation, meaning that while most scientists believe that dogs and wolves separated 10-15,000 years ago, others suggest that it might actually be over 100,000 years.
Explore more on the evolution of animals
-
School activities: Evolutionary tree of mammals
Learn more to access more details of School activities: Evolutionary tree of mammalsThis introduction to the evolution of mammals considers Darwin's observations on mammals and how he noticed that species fell into natural groups. This free course, School activities: Evolutionary tree of mammals, looks at evidence from fossils and DNA to examine which mammals are most closely related to whales.
Level: 1 Introductory
Dogs can also be highly adapted to extreme environments; think of huskies in the arctic or mammals that live in hot and desert-like environments. Traits like panting in the heat are examples of behavioural traits in dogs that exist in other mammals that live in extreme environments, such as deserts.
-
Animals at the extremes: the desert environment
Learn more to access more details of Animals at the extremes: the desert environmentAnimal life has adapted to survive in the most unlikely and inhospitable habitats. This free course, Animals at the extremes: the desert environment, looks at the surprisingly diverse desert climates throughout the world and mammals, birds, lizards and amphibians that survive there. It splits these animals into three groups according to their ...
Level: 2 Intermediate
‘How does your dog smell?’ ‘Terrible!’
Used in military and police services around the world, a dog’s sense of smell is renowned. Through selective breeding, some domestic dogs have an incredible sense of smell, being able to detect, distinguish and report on various smells such as explosives, money, drugs etc. Our ability to smell comes from protein in our noses that detects chemicals that evaporate from substances. These proteins are coded for by olfactory genes and as smell is so important, there are a lot of them in most mammals.
Do you know how many numbers of genes you have that encode smell receptors? The platypus has 260, humans have 380, dogs have 800, mice have 1000, and rats have 1200.
For primates such as humans, smell is less important as they have three-colour vision (red, green and blue), but animals that rely on smell, like mice, and are active at night in the dark, have many more. Dogs also have less well-developed colour vision than humans (they see only two colours, so they don’t see red very well… hence asking a dog to chase a red toy is always tough!) but they have over twice as many smell receptors than humans.
-
Studying mammals: Meat eaters
Learn more to access more details of Studying mammals: Meat eatersThe powerful and majestic carnivores are the focus of many television documentaries. In this free course, Studying mammals: Meat eaters, we will delve into the lives of these fearsome hunters and explore their physical adaptations and social behaviour. This is the fifth course in the Studying mammals series.
Level: 1 Introductory
-
Studying mammals: Return to the water
Learn more to access more details of Studying mammals: Return to the waterSome of the most unusual and versatile of all the mammals are the groups that live, feed and reproduce underwater. In this free course, Studying mammals: Return to the water, we will see how these formerly land-based mammals adapted to a return to the water, discussing such challenges as breathing, movement and communication. This is the seventh...
-
Studying mammals: The insect hunters
Learn more to access more details of Studying mammals: The insect huntersFrom pygmy shrews to armadillos, a wide range of mammals survive on a diet made up largely of insects. Many of these have fascinating adaptations suited to catching or rooting out their prey. In this free course, Studying mammals: The insect hunters, you will learn about these adaptations, along with survival strategies for when food is scarce. ...
-
Studying mammals: The social climbers
Learn more to access more details of Studying mammals: The social climbersMonkeys have long fascinated us because of their similarities to the human race. In this free course, Studying mammals: The social climbers, you will find out about some of the characteristics that make them so like us: their physiology, complex social interactions, large brains and intelligence. This is the ninth course in the Studying mammals ...
-
Studying mammals: Life in the trees
Learn more to access more details of Studying mammals: Life in the treesDavid Attenborough looks at life in the trees: examining how species have evolved to cope with arboreal living. In this free course, Studying mammals: Life in the trees, you will learn how lemurs, anteaters, bears and many others have developed different methods to help movement and survival.
-
Studying mammals: The opportunists
Learn more to access more details of Studying mammals: The opportunistsMany mammals are food specialists, with complex adaptations that gear them toward a particular food source. So how do the omnivores survive and prosper without these fancy evolutionary features? This free course, Studying mammals: The opportunists, examines the physiology, diet and strategies of some of these opportunistic feeders. It is the ...
-
Studying mammals: Meat eaters
Learn more to access more details of Studying mammals: Meat eatersThe powerful and majestic carnivores are the focus of many television documentaries. In this free course, Studying mammals: Meat eaters, we will delve into the lives of these fearsome hunters and explore their physical adaptations and social behaviour. This is the fifth course in the Studying mammals series.
-
Studying mammals: Plant predators
Learn more to access more details of Studying mammals: Plant predatorsFrom the mouse-deer to the elephant, plant eaters come in all shapes and sizes. But how do they manage to flourish on a salad diet? In this free course, Studying mammals: Plant predators, we will examine the special features that allow them to extract their nutrients from leaves, and see how some plants protect themselves from these predators. ...
-
Studying mammals: Chisellers
Learn more to access more details of Studying mammals: ChisellersEver wondered why rats, mice and squirrels seem to reproduce at such an alarming rate? Rodents are among the most successful of all the mammal groups. In this free course, Studying mammals: Chisellers, you will learn more about some of the evolutionary features that make these creatures so plentiful. This is the third course in the Studying ...
-
Studying mammals: Food for thought
Learn more to access more details of Studying mammals: Food for thoughtWho were our ancestors? How are apes and humans related? And where does the extinct Homo erectus fit into the puzzle? In this free course, Studying mammals: Food for thought, we will examine culture, tool use and social structure in both apes and humans to gain an understanding of where we come from and why we behave as we do. This is the tenth ...
Rate and Review
Rate this article
Review this article
Log into OpenLearn to leave reviews and join in the conversation.
Article reviews