IELTS Writing Task 1 evaluates your ability to describe and analyze visual information from various types of charts and diagrams. Among these, process or diagram questions can be especially challenging, requiring logical thinking and topic-specific vocabulary. One such topic that candidates often find difficult is the horse evolution diagram – showing changes in the structure of the horse's foot over 40 million years.
In this article, we will break down the task, outline an effective structure, and provide useful vocabulary and a high-scoring sample answer to help you approach complex process diagrams in IELTS Writing Task 1 with confidence.
1. Task Analysis – IELTS Writing Task 1: Horse Evolution
Task: You should spend about 20 minutes on this task.
The diagrams below show the development of the horse over a period of 40 million years. Summarize the information by selecting and reporting the main features, and make comparisons where relevant.
Write at least 150 words.
Question type: Process/Diagram
You are required to describe a sequence of changes or stages over time.
Key requirements:
Describe the evolution of the horse’s body structure, focusing especially on foot development and environmental adaptation
Highlight major changes such as body size, number and structure of toes, and adaptation to different habitats
Include comparisons across stages as the diagram spans several time periods
Write at least 150 words, ideally 160 to 190 words for full coverage without excessive detail
2. Suggested Outline for the Horse Evolution Task
Introduction
Paraphrase the question to introduce the topic clearly.
Example:
The diagram illustrates the evolutionary development of the horse over a 40-million-year period, focusing on the physical changes in its foot and overall appearance.
Overview
Summarize the most significant changes throughout the timeline.
Include points such as:
Clear transformation in foot and toe structure
Environmental adaptation
Trend from multi-toed, forest-dwelling species to single-hoofed, grassland species
Example:
Overall, the horse has undergone significant transformations, especially in terms of leg structure and foot development, evolving from a small forest-dwelling animal with multiple toes to a large, single-hoofed mammal.
Body Paragraph 1 – Early Stages
Describe the first two stages:
40 million years ago (Eohippus): small, four toes, lived in forests
30 million years ago (Mesohippus): slightly larger, three toes, open environment
Body Paragraph 2 – Later Stages
Describe the following stages:
15 million years ago (Merychippus): larger size, three toes but middle one becomes dominant
Modern horse: single hoof, long legs, adapted to grasslands
3. Sample Answer – IELTS Writing Task 1: Horse Evolution
The diagram illustrates the evolutionary saga of the horse over a 40-million-year period, with a particular focus on changes in foot structure. Overall, it is evident that as horses evolved, their bodies grew in size while their feet gradually transformed from having multiple toes into a single hoof.
The earliest ancestor, the Eohippus (40 million years ago), had a small frame and four slender toes. Approximately 10 million years later, the Mesohippus appeared with a slightly larger body and only three toes, the central one being thicker and more pronounced. This adaptation likely provided greater stability and support.
By 15 million years ago, the Merychippus emerged, further increasing in body mass and foot specialization. At this point, the middle toe had become more dominant, while the side toes diminished in size.
Finally, the modern horse showcases the culmination of this evolutionary trend. It is significantly larger, possesses a fully developed mane, and has a single, robust hoof formed by the fusion of previous toes—well-suited to support its greater body weight and enable efficient movement across various terrains.
High-Scoring Vocabulary for Horse Evolution Task
Vocabulary related to evolution and change: evolve, development, transformation, adaptation, modification, transition, emergence, characteristics, traits, species, ancestors, descendants
Vocabulary to describe size or quantity: increase, decrease, grow, shrink, larger, smaller, reduction, expansion
Vocabulary for body structure: toes, hooves, pads, limbs, body size, molars, teeth
Vocabulary for habitat/environment: forests, grasslands, plains, swamps
Vocabulary for describing process and time: gradually, progressively, sequentially, initially, subsequently, following this, at this stage, ultimately, finally, over millions of years, during the [Era] period
Confidently Tackle Process Diagrams with IDP
The analysis of the horse evolution diagram not only provides a model answer for a process-type task in IELTS Writing Task 1 but also emphasizes the importance of preparation in grammar, vocabulary, and structure. Once you master the skill of describing processes in chronological order and include relevant comparisons with academic language, you will be well-equipped to score high in the IELTS Academic Writing test.
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