Why the Big Toe Matters: How Evolution Shaped the Human Foot for Walking and Running

21 September 2026

By Mark Reyneker, BTech (Podiatry), MSc (Palaeontology), Registered Podiatrist, Foot & Gait Specialist | Founder & Clinical Director, Family Podiatry Centre

Why is the big toe so important?

The big toe, or hallux, plays an important role in human balance, walking and running. During late stance, the big toe bends upward as the heel rises, helping tension the plantar fascia, stiffen the foot and provide a stable forefoot for propulsion.

Its importance also reflects our evolutionary history. Early primate-like ancestors had a more divergent big toe suited to grasping. During human evolution, the hallux became aligned with the other toes as the foot became increasingly adapted for habitual walking on two legs.

The result is the distinctive human big toe: a large, relatively straight digit integrated with the first metatarsal, sesamoids, plantar fascia and foot muscles. Pain, arthritis, deformity or loss of movement at this joint can therefore change how forces pass through the foot during walking and running.

The Big Toe: How Evolution Turned a Grasping Digit into the Engine of the Human Foot

Most people do not think very much about their big toe until something goes wrong with it.

As a podiatrist, however, I spend a considerable amount of time thinking about the big toe. Pain, stiffness, arthritis, hallux valgus, sesamoid problems and restricted movement of the first metatarsophalangeal joint can all alter the way a person walks. Sometimes the change is subtle. Sometimes the entire propulsive strategy of the foot appears to change.

My interest in the big toe also extends beyond clinical podiatry. My postgraduate research in palaeontology examined the cross-sectional geometry of the human metatarsals and its relationship to high-gear and low-gear propulsion (Reyneker, 2022). Looking at the foot from both perspectives — as a clinician and as a palaeoanthropologist — makes the big toe particularly fascinating.

Because the human big toe is not simply a large version of our other toes.

It represents one of the most important transformations in the evolution of the human foot.

Our distant primate ancestors possessed feet capable of grasping. The first digit could diverge from the other toes and participate in gripping branches. During hominin evolution, that arrangement changed dramatically. The hallux moved into line with the other toes, became incorporated into a progressively stiffer forefoot and eventually became an important component of the propulsive system used during human walking and running.

In other words, evolution largely sacrificed prehension for propulsion.

And the anatomy of your big toe today still carries the evidence of that transformation.

The big toe is really a mechanical system

Anatomically, what we casually call the “big toe” is the hallux.

Unlike toes two to five, which normally contain three phalanges, the hallux usually contains only two: a proximal and distal phalanx.

But clinically, thinking only about those two bones misses most of the story.

The functional unit includes the:

first metatarsal
proximal and distal hallucal phalanges
first metatarsophalangeal joint
first tarsometatarsal joint
medial cuneiform
tibial and fibular sesamoids
plantar plate and joint capsule
plantar fascia
flexor hallucis longus
flexor hallucis brevis
extensor hallucis longus
abductor hallucis
adductor hallucis
and several ligamentous structures.

Collectively, these structures form what clinicians often describe as the first ray and hallux complex.

The first metatarsal is substantially more robust than the lesser metatarsals. Beneath its head sit two sesamoid bones embedded within the tendons of flexor hallucis brevis.

These sesamoids are not insignificant accessory bones.

They increase the mechanical advantage of the flexor apparatus, help transmit considerable loads beneath the first metatarsal head and provide a sophisticated pulley system around which the first metatarsophalangeal joint operates.

This is already a clue to the importance of the medial forefoot.

The human foot has effectively constructed a reinforced mechanical apparatus beneath the big toe.

Before propulsion came grasping

To understand why our big toe looks the way it does, it helps to look at another primate foot.

Chimpanzees possess a hallux that diverges substantially from the remaining digits. Functionally, this creates something much closer to a grasping structure.

The difference is immediately obvious when comparing human and chimpanzee feet.

In modern humans, the hallux is strongly adducted — positioned approximately parallel with the remaining toes.

In African apes it is considerably more abducted, allowing the foot to participate in grasping.

That distinction reflects fundamentally different locomotor requirements.

For an animal moving through trees, being able to wrap the foot around a branch is extremely useful.

For an animal repeatedly moving across the ground on two legs, however, a divergent grasping toe presents a mechanical problem.

A terrestrial biped benefits from a stable platform capable of accepting body weight and subsequently transmitting force into the ground.

Bringing the hallux into line with the other metatarsals transformed what had once been part of a grasping apparatus into part of a propulsive forefoot.

This transformation did not occur suddenly.

The fossil record suggests that hominin feet passed through a complex mosaic of locomotor configurations rather than progressing neatly from an “ape foot” to a “human foot” (Holowka and Lieberman, 2018).

Ardipithecus: a big toe that still grasped

One of the most informative early hominins is Ardipithecus ramidus, dating to approximately 4.4 million years ago.

Its foot is extraordinary because it combines characteristics associated with terrestrial bipedality with a markedly abducted hallux.

The big toe remained capable of substantial grasping.

Lovejoy and colleagues (2009) interpreted the Ardipithecus foot as a fascinating locomotor compromise: capable of terrestrial bipedalism but retaining a powerful hallucal grasping mechanism useful in an arboreal environment.

Whatever the exact reconstruction of Ardipithecus locomotion — an area that remains debated — one point is particularly important.

The modern human propulsive hallux had not yet appeared.

The big toe was still, to a considerable degree, a grasping digit.

Something remarkable had happened by 3.66 million years ago

Fast forward roughly 700,000 years and the evidence becomes particularly interesting.

At Laetoli in Tanzania, volcanic ash preserved extraordinary hominin footprints approximately 3.66 million years old.

These footprints are usually associated with Australopithecus afarensis.

The Laetoli footprints have been studied repeatedly because footprints provide something bones cannot: a direct record of how a foot interacted with the ground.

Analyses have identified several surprisingly human-like characteristics, including evidence consistent with:

an adducted hallux
a functional longitudinal arch
lateral-to-medial transfer of loading
and propulsion involving the hallux.

Crompton and colleagues (2012), using topographic analysis, experimental footprint formation and computer simulation, concluded that important aspects of modern human-like external foot function were already present approximately 3.66 million years ago.

That does not mean an Australopithecus afarensis foot functioned exactly like ours.

Indeed, comparative studies of metatarsophalangeal morphology suggest that A. afarensis probably differed from modern humans in forefoot dorsiflexion and push-off mechanics (Fernández et al., 2016).

But something fundamental had changed.

The big toe was becoming integrated into the direction of travel.

The foot was becoming a propulsive structure.

The rest of the foot was changing too

The evolutionary story of the hallux cannot be separated from the evolution of the rest of the foot.

This is important.

It is tempting to imagine that evolution simply moved the big toe inward.

The actual transformation was much more extensive.

The human lineage developed a suite of interacting features including:

hallucal adduction
shorter toes
changes in metatarsal head morphology
increasing midfoot stiffness
longitudinal arch development
transverse arch development
changes in plantar soft tissues
altered muscular function
and changes in the geometry and loading of the metatarsals.

A complete fourth metatarsal attributed to Australopithecus afarensis, for example, displays morphology consistent with longitudinal and transverse arching and a relatively stiff lateral foot (Ward et al., 2011).

More recent biomechanical work has also challenged the traditional tendency to attribute human foot stiffness almost entirely to the medial longitudinal arch.

Venkadesan and colleagues (2020) demonstrated that the transverse arch contributes substantially to longitudinal foot stiffness.

This matters enormously when thinking about evolution.

A propulsive hallux is useful only if the structures behind it can transmit force effectively.

The evolution of the big toe therefore occurred as part of the evolution of an integrated mechanical system.

From a grasping foot to a spring-loaded lever

The modern human foot has to perform two apparently contradictory jobs.

It must deform.

And it must resist deformation.

When the foot contacts the ground, some compliance is advantageous. The foot must accommodate the surface beneath it and manage loading.

But during propulsion the requirement changes.

Now the foot must provide sufficient stiffness to transmit force.

The human foot therefore behaves less like a simple rigid lever and more like a dynamically adjustable mechanical structure.

This is where the hallux becomes particularly important.

As the heel rises during late stance, the first metatarsophalangeal joint dorsiflexes.

That apparently simple movement influences structures extending far beyond the toe itself.

The big toe and the windlass mechanism

One of the classic explanations of this process was provided by J.H. Hicks in 1954.

The plantar fascia originates around the calcaneus and travels forward beneath the foot before dividing distally toward the toes.

When the toes — particularly the hallux — dorsiflex, the plantar fascia is wound around the metatarsal heads.

Hicks compared this to a windlass.

Imagine winding a cable around a drum.

As the cable winds around the drum, the effective distance between its attachment points shortens.

In the foot, dorsiflexion of the hallux increases tension within the plantar aponeurosis and can contribute to elevation and stiffening of the longitudinal arch.

This is the famous windlass mechanism.

The concept remains extremely influential in podiatry.

Modern biomechanics, however, suggests that the foot is more complicated than a purely passive windlass.

The plantar fascia can store and return elastic energy, the intrinsic muscles actively influence foot behaviour, and both longitudinal and transverse architecture contribute to stiffness.

The windlass is therefore best understood as one component within a much larger integrated system rather than as the single explanation for human foot function.

The plantar fascia may itself have an evolutionary history

Interestingly, the plantar aponeurosis did not simply appear when humans started walking upright.

Comparative anatomical work suggests that humans probably inherited much of its basic anatomical configuration from earlier primates.

What appears to have changed is how the structure was incorporated into the increasingly arched and stiff human foot.

Farris and colleagues (2020) proposed that hominins may subsequently have evolved a thicker and stiffer plantar aponeurosis as the longitudinal arch evolved, enhancing both windlass function and elastic energy storage.

This is a beautiful example of evolutionary modification.

Evolution does not always invent an entirely new structure.

Sometimes an existing structure acquires a new mechanical role.

Why the human big toe bends upwards

Another distinctive feature of the human forefoot is the capacity for substantial dorsiflexion at the metatarsophalangeal joints during propulsion.

Humans demonstrate greater MTP joint dorsiflexion than chimpanzees, with the largest interspecific difference occurring at the first metatarsophalangeal joint (Fernández et al., 2016).

This relates partly to the shape of our metatarsal heads.

As the heel rises, the leg and body continue moving forward while the hallux remains in contact with the ground.

The first MTP joint therefore dorsiflexes.

This accomplishes several things almost simultaneously:

The plantar fascia becomes tensioned.

The longitudinal arch can stiffen.

The centre of pressure can progress towards the medial forefoot.

The foot develops an increasingly stable platform for propulsion.

And eventually the hallux itself becomes one of the final points through which force is transferred to the ground.

This is why restriction of the first MTP joint is biomechanically significant.

Experimental restriction of first MTP movement alters normal walking mechanics (Xu et al., 2014).

The body can continue walking, of course.

But it has to solve the mechanical problem differently.

High gear and low gear: not every foot pushes off through the big toe in the same way

This brings us to an area particularly relevant to my own research.

In 1979, Bojsen-Møller described different propulsive axes within the human forefoot.

A high-gear strategy involves propulsion predominantly through the medial forefoot, particularly around the first and second metatarsal heads.

A low-gear strategy shifts the propulsive axis more obliquely across the lesser metatarsals.

The terminology comes from the mechanical consequences of changing the effective lever through which the foot operates.

The important point is that the human forefoot possesses more than one potential propulsive strategy.

This is something I subsequently explored in my MSc research at the University of the Witwatersrand.

I investigated metatarsal diaphyseal cross-sectional geometry in human populations and examined how structural differences across the metatarsals might relate to high- and low-gear propulsion (Reyneker, 2022).

That research reinforced something that I believe is clinically important:

the human forefoot should not necessarily be viewed as having one universally identical loading pattern.

There is considerable variation.

Different individuals and populations may distribute load through their metatarsals differently.

That becomes particularly interesting when archaeological populations are considered.

Bones remember loading — imperfectly, but importantly

Bone is a living tissue.

Over time, its architecture responds to its mechanical environment.

That means anthropologists can investigate cross-sectional properties of long bones and metatarsals to explore aspects of habitual loading.

The interpretation requires caution because bone morphology reflects genetics, development, body size, age, activity and many interacting biological influences.

Nevertheless, metatarsal structure provides an intriguing window into habitual foot loading.

Hagihara and Nara (2018), for example, investigated the cross-sectional geometry of metatarsals in Jomon hunter-gatherers and modern Japanese individuals.

The Jomon sample showed relatively greater structural properties in several of the lateral metatarsals.

The authors proposed that this could reflect heavier and more mediolaterally distributed forefoot loading, potentially associated with habitual movement over uneven terrain.

My own research similarly explored structural differences among the metatarsals in populations representing different habitual environments and locomotor histories (Reyneker, 2022).

This becomes relevant to the big toe because the evolutionary development of a powerful medial propulsive system did not mean that every human subsequently became mechanically dependent upon an identical hallux-dominated gait.

Humans remain remarkably variable.

We inherited a foot capable of medial propulsion.

We did not inherit a requirement that every step must use precisely the same loading pathway.

The Jomon foot is particularly interesting

The Jomon provide a useful example of why we should be cautious about defining a single “normal” human foot.

These hunter-gatherer populations lived in environments and engaged in habitual activities very different from those of contemporary urban populations.

Cross-sectional geometric evidence suggests relatively substantial loading of the lateral metatarsals compared with modern Japanese samples (Hagihara and Nara, 2018).

That does not mean the Jomon lacked functional big toes.

Rather, it suggests that the entire forefoot participated in locomotion in ways influenced by behaviour and environment.

From a clinical perspective, I find this fascinating.

Modern podiatry frequently attempts to classify feet according to fairly narrow models of ideal movement.

Palaeoanthropology reminds us that human locomotion contains considerable biological variability.

The big toe is enormously important.

But it operates as part of a five-ray forefoot.

Why did our toes become shorter?

Hallucal adduction was not the only major evolutionary change.

Human toes also became comparatively short.

Rolian and colleagues (2009) investigated the biomechanical consequences of toe length during walking and running.

Their results suggested that longer toes do not dramatically increase digital flexor requirements during ordinary walking.

Running is different.

Longer toes substantially increase the mechanical demands placed upon the digital flexors during running.

The authors proposed that shortened toes may therefore have been advantageous during the evolution of endurance running.

This is another important point.

The modern human hallux represents a compromise.

It is large and mechanically important but relatively short compared with the elongated grasping digits of arboreal primates.

We retained enough length to provide an effective lever.

But we lost the long, curved digits advantageous for grasping branches.

The resulting structure is extraordinarily well suited to terrestrial locomotion.

The big toe is also important for balance

Propulsion receives most of the attention, but the hallux has another important role.

Balance.

When standing, our centre of mass constantly moves slightly relative to the relatively small base formed by our feet.

The toes can apply forces against the ground to help control this movement.

Research in older adults has found hallux plantarflexion strength to be independently associated with measures of balance and functional ability (Menz et al., 2013).

Systematic review evidence similarly suggests that toe flexor strength is associated with postural balance in older adults (Quinlan et al., 2020).

This makes intuitive biomechanical sense.

The big toe sits at the medial and anterior boundary of our base of support.

It can therefore participate in controlling forward and medial displacement of pressure beneath the foot.

The hallux is not merely something we push from.

It is part of the sensory and muscular interface between the body and the ground.

What happens when the big toe stops moving properly?

This is where evolutionary anatomy becomes directly relevant to clinical podiatry.

The first MTP joint has evolved within a locomotor system in which dorsiflexion during late stance is normal.

If that movement becomes painful or restricted, the body still has to move forward.

It therefore adapts.

We may see changes in:

centre-of-pressure progression
forefoot loading
stride characteristics
lesser-metatarsal loading
foot progression angle
ankle mechanics
and sometimes more proximal lower-limb movement.

The precise compensation varies considerably between individuals.

That is important because a stiff big toe does not produce one universal compensatory gait.

Hallux rigidus: when an evolutionary joint becomes arthritic

Hallux rigidus is degenerative disease of the first metatarsophalangeal joint.

As cartilage deteriorates and osteophytes develop, dorsiflexion becomes increasingly restricted and frequently painful.

From an evolutionary perspective, it affects a joint positioned at one of the most mechanically important areas of the propulsive forefoot.

During late stance the body normally progresses over the first MTP joint.

When the joint cannot comfortably dorsiflex, patients may redirect load elsewhere.

Some roll towards the lateral forefoot.

Some externally rotate the foot.

Some shorten their stride.

Others continue loading the hallux but tolerate pain.

This is why simply measuring the static range of movement of the big toe tells us only part of the story.

What matters clinically is how the entire foot responds when the person actually walks.

Hallux valgus changes the system differently

Hallux valgus presents another fascinating mechanical problem.

Here the hallux progressively deviates laterally while the first metatarsal tends to deviate medially.

The sesamoid apparatus and soft tissues around the first MTP joint are progressively altered.

The digit that evolution brought into alignment with the direction of travel is gradually moving away from that alignment.

Systematic reviews of gait in people with hallux valgus demonstrate alterations in plantar loading, kinematics and kinetics, although the exact patterns vary between studies and with deformity severity.

Once again, the important concept is not that hallux valgus simply produces a “crooked toe”.

It changes a mechanical system.

The sesamoids: two small bones doing a very large job

The sesamoids deserve special mention because they are often overlooked.

There are normally two beneath the first metatarsal head.

They sit within the flexor hallucis brevis apparatus and articulate with grooves beneath the metatarsal.

Mechanically, they help maintain the moment arm of the flexor tendons as they pass beneath the first MTP joint.

This is comparable to moving a cable away from the centre of a pulley.

The farther the tendon operates from the joint's centre of rotation, the greater its potential moment arm.

The sesamoids therefore contribute to the remarkable mechanical specialization of the human first ray.

Their presence also helps explain why sesamoid pathology can be so disruptive.

These tiny bones sit directly within one of the most heavily loaded regions of the propulsive foot.

The big toe does not work alone

There is an important danger in discussing the hallux: making it sound as though the rest of the foot merely supports it.

That is not how human locomotion works.

The hallux depends upon the:

lesser metatarsals
transverse arch
longitudinal arch
plantar fascia
intrinsic musculature
peroneus longus
tibialis posterior
calf musculature
ankle
subtalar joint
midfoot
and the entire lower limb.

Research into intrinsic foot muscle function demonstrates this beautifully.

When intrinsic foot muscle activation is experimentally blocked, humans can still walk and run, but the distal foot becomes less capable of generating normal stiffness during push-off and compensatory changes occur elsewhere in the limb (Farris et al., 2019).

Human propulsion is therefore an emergent property of the entire lower limb.

The big toe occupies an exceptionally important position within that system, but it is not operating independently.

Perhaps we should stop calling it “push-off”

Even the familiar phrase push-off can be misleading.

It creates the impression that the big toe actively pushes the body forward like a piston.

Human propulsion is more sophisticated.

During late stance, the centre of mass is already progressing forward. The calf muscles generate substantial ankle plantarflexion moments. The heel rises. The centre of pressure moves anteriorly. The foot changes stiffness. The plantar tissues are tensioned. The first MTP joint dorsiflexes. Muscles spanning the foot and toes contribute to control and stiffness.

The hallux provides part of the final interface through which these forces interact with the ground.

So the big toe is not the engine by itself.

A better analogy might be the final gear in a transmission system.

The engine sits farther upstream.

But without an effective transmission, the power cannot be delivered efficiently.

Evolution did not create a perfectly rigid foot

One of the most interesting developments in modern foot biomechanics is the recognition that stiffness itself is variable.

For many years the human foot was commonly described as transforming from a “mobile adaptor” into a “rigid lever”.

That description is useful clinically but biologically oversimplified.

The foot does not literally become rigid.

It changes its stiffness.

Muscles, fascia, ligaments, joint geometry and loading all contribute.

That distinction matters because a perfectly rigid foot would actually lose many of the advantages of the human design.

We need deformation to absorb and store energy.

We need stiffness to transmit force.

Human foot evolution therefore appears to have produced something far more sophisticated than a rigid platform.

It produced a tunable spring-lever system.

And the hallux sits at the front of it.

What the fossil record teaches the podiatrist

For me, this is where palaeoanthropology becomes clinically useful.

When we look across several million years of hominin evolution, the human big toe tells a remarkable story.

Approximately 4.4 million years ago, Ardipithecus ramidus still possessed a strongly divergent, grasping hallux.

By approximately 3.66 million years ago, the Laetoli footprints indicate a much more human-like relationship between the hallux and terrestrial bipedal propulsion.

Australopithecus afarensis demonstrates other aspects of an increasingly stiff and arched foot.

Later members of the genus Homo show increasingly modern configurations.

The foot of Homo naledi, for example, possesses an adducted hallux, elongated tarsus and largely modern-human-like architecture associated with striding bipedalism, despite retaining some primitive characteristics (Harcourt-Smith et al., 2015).

The evolutionary trajectory is therefore not simply:

ape foot → human foot.

It is a mosaic.

Different components of the foot changed at different times.

Different hominins experimented, in an evolutionary sense, with different combinations of climbing and terrestrial locomotion.

But one trend becomes unmistakable.

As habitual terrestrial bipedalism became increasingly important, the hallux became progressively incorporated into the forefoot.

The grasping toe became a propulsive toe.

Why this matters today

Patients sometimes ask me:

“Do I really need my big toe to walk?”

Technically, humans are extraordinarily adaptable.

People can walk despite severe arthritis, deformity, surgical fusion and even loss of the hallux.

But that is not the same as saying the hallux is unimportant.

The human locomotor system is capable of compensation.

If one structure becomes unavailable, forces can be redistributed and movement strategies can change.

The fact that the body can compensate for loss of function tells us something remarkable about human adaptability.

It does not tell us that the original structure had no function.

Millions of years of evolutionary modification transformed the hallux from a grasping digit into a large, aligned and mechanically reinforced component of the human forefoot.

Its relationship with the first metatarsal, sesamoids, plantar fascia, intrinsic musculature and longitudinal and transverse arches allows it to participate in balance, foot stiffening, force transmission and propulsion.

Few parts of the human skeleton illustrate our evolutionary history quite so elegantly.

Look at a chimpanzee's foot and then look at your own.

The difference between those two big toes represents part of the story of how our ancestors left the trees, committed increasingly to life on the ground and eventually became extraordinarily capable walkers and runners.

For me, that is what makes the big toe so interesting.

It is not simply a toe.

It is an anatomical record of becoming human.

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Disclaimer: The word "treatment" in this article refers to the care and management of a patient’s health to prevent, cure, or improve a condition. Treatment results vary and do not necessarily indicate a cure. This article is for informational and educational purposes only and does not constitute medical advice.

About the Author

Mark B. Reyneker, BTech (Podiatry), MSc (Palaeontology) is a podiatrist and Founder & Clinical Director of Family Podiatry Centre, with more than 25 years of clinical experience across South Africa, Malaysia and Singapore. His clinical interests include foot and lower-limb pain, gait and biomechanics, sports-related foot conditions, orthotic therapy and footwear.

Alongside his clinical practice, Mark conducts research into human gait and foot biomechanics. His MSc research at the University of the Witwatersrand investigated human propulsion and the structural properties of the metatarsals. He is also the inventor of A Foot Orthotic, an orthotic technology developed through an international patent family.

References

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Available at: https://pubmed.ncbi.nlm.nih.gov/511760/
Crompton, R.H. et al. (2012) ‘Human-like external function of the foot, and fully upright gait, confirmed in the 3.66 million year old Laetoli hominin footprints by topographic statistics, experimental footprint-formation and computer simulation’, Journal of the Royal Society Interface, 9(69), pp. 707–719. Available at: https://pmc.ncbi.nlm.nih.gov/articles/PMC3284127/
Farris, D.J., Birch, J. and Kelly, L. (2020) ‘Foot stiffening during the push-off phase of human walking is linked to active muscle contraction, and not the windlass mechanism’, Journal of the Royal Society Interface, 17.
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Available at: https://pubmed.ncbi.nlm.nih.gov/30655349/
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Available at: https://www.nature.com/articles/srep30532
Hagihara, Y. and Nara, T. (2018) ‘Diaphyseal cross-sectional geometry of the metatarsal bones in the Jomon population’, American Journal of Physical Anthropology, 166(3), pp. 745–752.
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Available at: https://www.nature.com/articles/ncomms9432
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Available at: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0152602
Menz, H.B. et al. (2013) ‘Foot and ankle strength, range of motion, posture, and deformity are associated with balance and functional ability in older adults’, Archives of Physical Medicine and Rehabilitation.
Available at: https://pubmed.ncbi.nlm.nih.gov/21187207/
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Frequently Asked Questions

During late stance in walking, the heel rises and the first metatarsophalangeal joint dorsiflexes while pressure progresses toward the forefoot. This places the hallux at an important part of the foot-ground interface during propulsion. Big-toe dorsiflexion also interacts with the plantar fascia and the changing stiffness of the foot. Experimental restriction of first MTP joint movement has been shown to alter walking mechanics (Xu et al., 2014).

Often, but the biomechanics are more complicated than simply “pushing off the big toe.” Pressure generally progresses anteriorly and often medially during late stance, while the ankle plantarflexors, foot muscles, plantar tissues and forefoot work together. Humans can also use different propulsive axes, including the high-gear and low-gear mechanisms described by Bojsen-Møller (1979). My own MSc research investigated how these different propulsive strategies may relate to structural properties of the human metatarsals (Reyneker, 2022).

Our primate ancestors retained feet with greater grasping capability. A divergent hallux is useful for gripping during arboreal locomotion, but the human lineage progressively incorporated the hallux into a foot specialised for terrestrial bipedalism. Ardipithecus ramidus, approximately 4.4 million years old, retained a markedly abducted grasping hallux, whereas later hominins show increasingly human-like forefoot characteristics (Lovejoy et al., 2009; Holowka and Lieberman, 2018).

Some early hominins retained a substantially more divergent and grasp-capable hallux than modern humans. Ardipithecus ramidus is an important example. However, human foot evolution was mosaic rather than a simple transition from an “ape foot” to a modern foot. Different anatomical components changed at different times (Lovejoy et al., 2009; Holowka and Lieberman, 2018).

There was probably no single moment when this occurred. Ardipithecus, at about 4.4 million years ago, retained a divergent hallux, while the approximately 3.66-million-year-old Laetoli footprints provide evidence of substantially more human-like bipedal foot function. The transformation therefore occurred progressively within early hominin evolution rather than as a single anatomical event (Crompton et al., 2012).

Yes. The hallux occupies the medial-anterior part of the base of support and can generate plantarflexion force against the ground. Research in older adults has associated hallux and toe strength with balance and functional performance, although balance obviously depends on many other sensory, muscular and neurological systems as well (Menz et al., 2013; Quinlan et al., 2020).

As the heel rises and the body progresses forward, the first MTP joint normally dorsiflexes. This movement interacts with the plantar fascia, first ray, sesamoids and surrounding muscles and contributes to the changing mechanical behaviour of the foot during late stance. The classic explanation is Hicks' (1954) windlass mechanism, although modern research shows that active muscle contraction and other aspects of foot architecture also contribute to foot stiffness.

Reduced or painful first MTP movement can alter how a person progresses over the forefoot. Possible adaptations include changing foot progression, shortening stride, redistributing pressure toward the lesser metatarsals or modifying ankle and lower-limb mechanics. The exact response varies between individuals, which is why a stiff big toe should be assessed as part of the entire gait system rather than in isolation.

Yes. Humans are capable of substantial locomotor compensation following loss or severe dysfunction of individual foot structures. However, being able to compensate does not mean the hallux is functionally unimportant. Its anatomy and position make it an important contributor to balance, forefoot loading and late-stance propulsion.

The hallux forms part of a highly specialised medial forefoot complex that includes the robust first metatarsal, two sesamoids, powerful flexor muscles and substantial plantar soft tissues. Rather than functioning primarily as a grasping digit, as in many other primates, the human hallux has become incorporated into a forefoot capable of accepting and transmitting substantial loads during bipedal locomotion.