Preliminary investigation of morphological differences between ten breeds of horses suggests selection for paedomorphosis.

This research study explores the morphological differences in ten horse breeds, pointing towards a concept called ‘paedomorphosis’, the retention of juvenile traits into adulthood, which could hint at evolutionary changes in domestic species.

Understanding Paedomorphosis

• Paedomorphosis is a concept in evolutionary biology that denotes the retention of juvenile characteristics in the mature form of a species. This pattern of growth is known to play a significant role in the evolutionary transformation of both domestic and wild species.
• The correlation between this evolutionary phenomenon and morphological (physical and structural) differences, behavioral aspects and physiological characteristics amongst varying breeds forms the core of this investigation. It thus provides insights on possible evolutionary transformations.

Investigation Approach

• The study engaged in a comparative analysis of the physical traits of 10 horse breeds from Northern and Southern regions. The comparison was done with the Exmoor pony, a breed native to the British Isles.
• The investigation received inputs from 23 respondents based out of the United Kingdom and Australia. They rated each breed based on seven physical traits.
• The physical traits included factors such as the size of the horse’s head, the length of their legs, and the ratio of their head size to body size.

Findings and Implications

• The study demonstrates a high degree of agreement amongst the respondents as depicted by low standard deviations.
• The analysis ranks the horse breeds from the ones most similar to the Exmoor pony (Highland pony) to the least similar (Arabian).
• The breeds that were found to be the least similar to the Exmoor pony exhibited physical traits suggesting paedomorphosis.
• These physical traits are characterized by small heads, long legs, and a diminished head-to-body ratio, traits generally exhibited by juvenile horses but are retained into their maturity.
• The research thus indicates that morphological, behavioural, and physiological differences amongst the breeds, and comparing extant breeds with the faunal remains of pre-domestication horses, could justify a more in-depth exploration of the subject.

In conclusion, this preliminary study throws light on the potential influence of paedomorphosis in the evolutionary transformation seen in domestic horse breeds. This investigation provides a foundation for further detailed exploration and comprehensive study.