What in the Whorl…?!

Between 2012 and 2015, my interests surrounding whorl placement in horses, the mythical relationship with temperament analysis and the part that a colour of a horse plays in its genetic make up came to a head, and I focussed my University Dissertation efforts into this subject for the duration of this period.

Have you ever wondered why we all refer to chestnut mares as ‘a little crazy’ or why your physio always comments on your horse being notably stiffer to one side, or that he always spooks the same way, from the same side?

This is Part 1 of this 2 part insight into what we can learn about common ideas from whorls, colours, the intricacy of behaviour, and genetics.

Traditionally, hair whorls on the horse have been used to determine fortune, intelligence or value, but have been recognised for other reasons including a role in genetics colours, breeds, hormones and brain function. Many studies have been conducted into ‘whorlology’, mostly focussing on motor laterality; dependant on position and direction of whorls in dogs, cattle, mice and horses.

There are potential relationships between temperament and whorl characteristics due to formation from the brain, hair follicles, and nervous system. This may have an impact on brain use and therefore emotional state, fear response, ability to focus and normal behaviour – all factors we look at when assessing horses’ temperament and suitability for careers.

When interpreting any information, factors such as evolution and domestication must be taken into consideration, as well as environmental and geographic factors, gender, education and age.

The Ten Traits

It is believed that the horse has ten traits, regardless of an external or internal factors, whether feral or domesticated.  Each trait links to all the others, and are equally important in training, management and understanding horse behaviour. They are controlled by the senses, which receive instruction from the brain, nervous and endocrine systems. Because horses are a precocial species (neurologically mature at birth), what happens to them soon after birth can be influential to the rest of its life. This is fundamental in temperament assessment – using whorls or not!

The Ten Traits are:

• Flight – primary survival behaviour – run!
• Perception – referred to as the sixth sense – detection of sensory stimuli too vague for humans, integral for survival
• Response Time – ability to perceive stimuli and react
• Rapid Desensitisation – a horse must learn quickly to desensitise against frightening but harmless stimuli
• Learning – Goes hand in hand with above
• Memory – Hand in hand with above two points – a horse must remember things it has learned.
• Dominance Hierarchy – integral to the flight response due to requirement of leadership – people can take place of this in a domesticated environment
• Control of Movement – horses exert dominance by control of movement. Positional control can save a life through use of pressure and release.
• Body Language – subtle but very visual tool
• Precocity – neurologically mature at birth – integral to survive in the wild. Predator species do not imprint as quickly as prey species.

Other Influential factors to Temperament

The Nervous System

The immediate reaction of the sympathetic nervous system induces involuntary actions including diversion of blood away from the least needed organs, such as the digestive tract, causing defecation during stressful situations. The slower secretion of cortisol is released by the adrenal cortex of the fore brain, as signalled by the endocrine glands. Both reactions are measurable traits of emotional state used in observational studies.

Hormones

Hormones control behaviour and dictate bodily functions. They are secreted into the sensory (SNS) and central nervous system (CNS). A negative emotional state and a positive motivation can cause compulsive behaviour, activated by the SNS and the hypothalamic pituitary adrenal system, which are associated with negative emotions (and Cushing’s disease). The mouth is extremely important in behaviour assessment as when chewing, the salivary glands produce fluid that triggers the parasympathetic nervous system, relaxing the horse and quietening the SNS which is responsible for the flight response. This is the bit that is so highly sought after during ‘join – up’ and is often a sign humans take as the horse processing instructions.

Environment

Housing and breeding have both been found to impact behaviour and shape behaviour responses in horses. Stabled horses have been seen to react and display more expressive movement to a novel object test more than those with paddock housing. Placement, how they are distributed and symmetry of whorls across the body has also been found to be a significant factor in susceptibility of developing stereotypes in Thoroughbreds, although reasons why are yet to be investigated fully.

Nutrition

We all know that how much food, or what food, a horse gets fed can affect its temperament. Take spring grass – they all go a little wild! Take spring grass for insta – they all go a little wild! Reactivity scores were analysed of high and low starch diets, and found the high starch induced increased glycaemic response, which influences behaviour and reactivity. It has also been suggested horses fed a carbohydrate rich diet are more reactive, coupled with a higher heart rate. High fat diets have also been tested, finding that horses produce a less intense startle reaction, and a lower cortisol concentration and heart rate.

Breeding

Temperament has been suggested to be heritable as it consists of biologically rooted individual behaviour tendencies. Sire influences are evident in emotionality, with a tendency to develop stereotypical behaviour as a response to stress.

Environmental conditions in different geographical regions have resulted in inevitable changes in horses during evolution too, which are reflected in the diversity of present breeds.

Traditional Values

Arabian horses have been historically associated with legend and spiritual beliefs, especially to the Bedouin people who placed great faith in colours, markings and whorl patterns to determine value. Native North American people specified their choice of horse by size, colour and resistance whereas Arab horses were selected based on characteristics such as chest width or eye size, supposedly indicative of intelligence or courage.

Colours

The table below briefly explores reasons behind their colour choices – have a think about how we still attribute to some of these today in a modern way – bays are always considered most genuine and plain!

Piebaldism

There is a scientific explanation to the bizarre dislike of coloured horses. Some animals with large piebald spots on the head and body may have neurological defects similar to the genetic defect known as piebaldism in people, affecting eyesight and hearing, and therefore balance.

Piebaldism is also referred to as ‘white spotting’. The gene responsible for the occurrence in mice and horses is the endothelin receptor B gene and is associated with deafness and aganglionic megacolon (condition where certain nerve cells are missing from the muscle layers of part of the large intestine) in horses and humans, deafness in dogs, cats, humans, and also with lethal white foal syndrome.

An anecdotal article mentions associations between placid behaviour and piebaldism; coloured horses are often considered ‘plods’. This is supported by other published sources, which also have found that alongside domesticated animals becoming smaller over time, white markings have appeared on their coats, which is genetically linked to gentle behaviour.

However, there is a relationship between depigmentation, albino genes, spot genes and nervous problems, and attention must be diverted toward the development of the embryo to understand why.

The developing embryo has a neural tube and crest down its back, responsible for supplying melanocytes. These attach to the base of hair follicles and synthesise melanin which is the pigment responsible for hair and skin colour; it is then fed into the hair. Mutation of the c-KIT gene causes piebaldism, creating a delay of the migration of the melanocytes; thus, areas furthest away from the midline (feet, chest, belly) result in depigmentation. This offers explanation of Bedouin peoples’ belief that leg markings could be a good or bad omen dependent on number and location – it is still something we sometimes mention today!

“One white foot, keep him not a day, Two white feet, send him far away, Three white feet, sell him to a friend, Four white feet, keep him to the end”

Melanocytes are connected to the CNS, which can heavily impact behaviour and mood. They are also present in the inner ear and eyes, suggesting a delay of melanocytes causing depigmentation of these areas could also cause deafness and blindness. Nervousness is also related to large areas of depigmented hair and skin, and blue eyes can be seen as an indicator of neurological problems, giving cause for concern over temperamental traits and ability to perform due to lack of sight.

There is little research surrounding blue eyes in horses, though melanin is responsible for the pigmentation. If it is at the back of the eye then the light scatters and the eye appears blue, whereas the closer to the front that the melanin reaches, the darker it will be. There are no suggestions that it specifically affects the ability of the horse to see.

Whorls in History

Arabians are said to have forty whorl locations, whereby twelve are significant. For example, a whorl under the mane (the finger of the prophet) meant that the master would die safely in his own bed. Others had a negative impact on the perceived value of the horse. A whorl beside the tail brought trouble, misery and famine, and a whorl on the fetlock (whorl of theft) meant that the horse prayed to be stolen or that its master would die.

Whorl Science

The relationship between whorl direction and motor laterality can affect movement, co-ordination and balance. Motor preferences of 104 left ‘handed’ horses compared with 95 right ‘handed’ horses and 20 well balanced horses were tested in a study and demonstrated a significant relationship between whorls and which rein they preferred to move on. One Hundred and Fourteen horses had counterclockwise whorls, (mostly left-handed group) 82 with clockwise whorls (mostly right-handed group) and 23 horses with radial whorls (mostly well-balanced group). This relationship between handedness and whorl direction was more than what would be expected by chance alone.

There has also been a relationship found between temperament and facial whorl position in Lundy ponies. Whorls placed to the left of centre correlated with a calmer and friendlier disposition whereas whorls displayed to the right displayed the opposite.

The Brain Hemisphere Relationship

A novel object test has been shown to demonstrate that horses favour their right eyes when exploring a positively valanced object, and the left eye for the negative object. This confirms the use of the role of the left hemisphere of the brain in assessing novelty, while the right side may process negative emotional responses.

A whorl positioned above the eye is indicative of a higher awareness of surroundings and environment, whereas if placed further down, the more ‘close-minded’ the horse may be. Symmetry, or occurrence rate of whorls either side of the whole body, must be accounted for as this can indicate the ability to focus, depending on how tightly shaped and geometric individual whorls are. Position refers to the location on that particular body segment, such as high or low, but does not consider the relationship with any other whorl. Studying symmetry attempts to look at whether there is a higher incidence on one side of the body than the other, which opens avenues to deciphering brain hemisphere use or handedness to one side.

A horse with a high whorl, may therefore be ‘spookier’, notably to the left – this would suggest a right brained, highly aware horse, and generally considered ‘sharp’. A horse with more whorls on the right side of the body may be more sensitive that side than the other, or may be prone to becoming tight. Whorls are directly connected to nerve endings (more to come on this) and therefore they can be more or less sensitive because of it.

Genetics

A link between whorl orientation and handedness in humans suggests that patterns are genetically passed on. Scalp hair patterning in humans is determined at 10 to 16 weeks’ gestation and is secondary to the growth and shape of tissues which underlie the skin, especially the brain.

In a review focussing on hair patterns of newborns, it is stated that scalp hair and patterns are associated with the development of the CNS, and that genetic, metabolic and neurologic disorders can be traced back to hair ‘abnormalities’. Development of the brain, spinal cord, CNS, hair and skin is all derived from the same ectoderm layer, whilst in the later stage of fetal development, hair growth occurs at an oblique angle to the skin and the whorl pattern is a result of scalp stretching occurring with brain growth. In people, hair density, structure and growth have been found to correlate with gender, race, and nutritional status, whilst the most common whorl position (left of midline) has been suggested to have a connection with a larger left side of the brain. The left side of the brain in humans is more responsible for awareness, problem solving and reasoning.

There is a theory that has been proposed that metabolic activity controls whorl characteristics, whilst the Frizzled-6 gene theory is more recent. The idea of this is that the gene plays a role in hair patterning; with targeted deletion of the gene in a study, resulted in an abundance of whorls on the hind feet and heads of mice.

Behaviour and structural traits (such as hair, build, etc) appear to share physiological processes too, and there is a relationship that suggests characteristics such as weight gain and posture and behaviour share the same chromosomal area as hair patterning and coat colour in mice. This could help in future to explain links in aggression and coat colour which may have leads for temperament in horses, mostly due to how serotonin (the feel-good hormone) and melanin (the colour creating cells) interact.

In Part 2 I will look at actual whorls in more detail and what height, placement, and what direction they turn can tell us about their temperament, and how these characteristics are linked to the points made throughout this article.