The mean impact velocity in this experiment provides data for replication studies, and while it largely confirms existing estimates of prehistoric spear throwing25,74, the spear replicas used in this study were of a higher mass, demonstrating that in skilled hands, such masses are not a limiting factor. According to the principle that the greater the mass of an object, the greater the work to propel that mass75, objects with lighter mass, such as those thrown by inexperienced throwers used for the calculations elsewhere25 would be expected to be thrown with significantly higher velocities by skilled throwers than those achieved in the present study using heavier spears. This is supported by the higher release velocities achieved with lighter thrown objects such as balls and sticks by skilled throwers (Supplementary Information Table S1). The range of velocities in the present study overlaps with velocities recorded for spearthrowers. The lack of a trend to drop in impact velocity from release differs from lighter and fletched projectiles such as arrows and darts, which experience more drag than a heavier unfletched spear (see Supplementary Information for further explanation). Overall the data from this experiment demonstrate that at short ranges in field conditions there is not a demonstrable loss in velocity and therefore KE or momentum from release to impact for spears such as those from Schöningen, and therefore the hypothesis that this is a significant limitation of the weapon is not supported. With different wind conditions and/or at greater distance throws there may be more significant velocity losses, though a recent javelin study also shows that loss in velocity from release to impact over longer distances can also be slight76. Further experimentation on this question would be useful.

Hand-thrown spears can impact with KE and momentum values that are suggested to be sufficient to hunt large prey77. Considering that it is impact energy, not just velocity, that influences penetration and fracture mechanics, these results are significant for those seeking to identify prehistoric weaponry delivery systems in the Pleistocene archaeological record using systematic mechanical projection. In addition to KE and momentum, other variables such as tip material and morphology affect penetration, influencing ability to cut through hide, muscle and bone, depth of penetration, and wound morphology. The spears used in this experiment have wide diameters in comparison with most complex projectiles, and do not have a stone tip. This study focuses on the external and terminal ballistics of the spears and does not address penetration and wounding capabilities, or overall effectiveness of these weapons, something that requires systematic experimentation.

The participants in this study, trained in throwing but not in aiming for a target, were able to hit the target at distances up to 20 m, though with a significant drop in accuracy at each distance. Their inability to hit a target at distances >20 m likely relates in part to their inexperience with target throwing, but additional factors most likely include the difficulty of aiming with a parabolic trajectory and the target height. It has been suggested that hitting a target with complex projectiles is a relatively easy skill to learn in comparison with other hunting skills77,78. This may or may not hold true for hand-thrown spears, which appear to require not only greater power to launch but are potentially more difficult to learn to reliably hit a target than spearthrower darts and arrows. The ethnographic evidence presented in this paper suggests that these skills can be learned for throwing, but that it may require years of regular practice to master, in turn affecting the number of hunters that a society may be able to deploy.

However, with practice in aiming improvement over the results in this experiment can be expected. Within our experiment, the participant with the best hit rate (33%) performed three times better than that with the worst hit rate (11%) (Supplementary Information Table S7). On the other hand, P2 with the most years throwing experience did not have the best hit rate (Supplementary Information Table S7), and thus other factors such as overall fitness and regular practice likely play a role. Body mass may also play a role in successful hit rates (Supplementary Information Fig. 7). Further supporting the importance of skill is the fact that our participants had an 11.4% improvement at the 15 m distance (25% hit rate) over the untrained participants in an experiment using the same size target, and replicas of the same spear (13.6% hit rate)28. Capturing data from groups trained in aimed throws, such as those skilled in use of the Roman pilae or extant hunter-gatherers, is a necessary step-wise experiment that will build upon current understanding of hand-delivered spears including whether skill, fitness or body mass play the most important role in accuracy, distance, and impact energy. We propose on the basis of ethnographic estimates and experimental data in this paper a conservative revision of distance estimates for hand-thrown spears of 15–20 m. This still likely represents a lower accuracy distance than complex projectiles, but the extent of the difference is not as great as is often suggested. The proposed revised estimate of 15–20 m is not intended to be definitive but rather to re-open the debate on this important question and invite further experimental use by trained throwers, and will take further naturalistic use of hand-thrown spears to better understand the true limitations of this delivery system.

On the basis of the experiment presented in this paper, two different throwing trajectories can be used. Flat trajectories at a target are an effective technique for shorter distances. At distances ≥15 m, hunters would need to use a parabolic trajectory, which decreases accuracy and requires more skill and strength. Distance throws were shown in this study to achieve significant impact KE and momentum, but frequently failed to land point first. Further studies will be necessary to understand whether this is a limitation of spears or due to the inexperience of most of our participants with stiffer javelins, typically used by elite throwing athletes (see Supplementary Information). This could in part explain why some throws experienced yawing as greater power is needed to accurately throw a stiffer spear. Spears such as those from Schöningen, manufactured from dense wood and with thick diameters, could also have been designed to match experienced and powerful throwers, balancing durability with aerodynamics, reflecting an understanding of material properties by Middle Pleistocene Homo.

The primary purpose of this paper was to replace problematic estimates of the external and terminal ballistics of hand-thrown spears by reviewing the existing evidence and collecting empirical data. The data support hypotheses that early spears, such as the double-tapered examples from Schöningen, function as throwing weapons both for flat and parabolic trajectories at distances up to 20 m. Our results underscore the importance of using trained participants if launching weapons manually in experimental research79 whether the aim be to further evaluate performance parameters or for replication work. In experimental work using human throwers, recording of impact velocities, accuracy data, and physical attributes and skill level of throwers will help fill in knowledge gaps. Unlike for spear thrusting, controlled mechanical replication of hand-thrown velocities is straightforward, but experimenters should carefully consider potential masses of hand-thrown spears as this affects external, terminal and wound ballistics. Replicating a mean statistic for weapon performance parameters while ignoring the range creates problems for comparing and identifying delivery systems. In particular replicating mean impact velocity and by extension KE and momentum rather than the range superficially suppresses human and technological variability, masks overlaps with other weapon systems, and may create false taxonomies.

The results imply that robust, highly-trained and habitual throwers could throw spears with more power and at least twice as far as has been widely argued for in the literature. The extension to a 20 m accuracy limit from this experiment implies greater flexibility in hunting strategies than the previous distance estimates. The larger ethnographic distances discussed would put hand-thrown spears on par with spearthrowers. In hunter-gatherer societies, the skills involved in hunting take decades to master, beginning in early childhood78. With both skill, strength and potentially a larger body size needed to use spears effectively as thrown weapons, we can theorize that only hominins that combined relatively large brains with robust physiques could have employed them as part of a successful subsistence strategy. These effective costs are high when compared to later complex projectiles that may have offered a relaxation on time and energy budgets required to learn and effectively use these ‘simple’ hunting technologies. The importance of skill in weapon use has been discussed elsewhere31,70,80, with an interesting hypothesis proposing that hand-delivered weapons are not inferior in terms of energy, but rather that part of their disadvantage relates to a high investment in training31. Understanding and explaining the development and persistence of hand-thrown weapons in the human past is complex and requires approaches from multiple disciplines. It is not the case that hand-thrown spears are universally replaced by complex projectiles, as they continued to be used, most typically alongside other weapon systems, through to the ethnographic present. Moreover we can compare this performance data with those from experiments demonstrating the potential of these weapons as thrusting spears, in order to consider the likelihood that they were routinely thrown at all. Understanding the fine detail of the situations, ecologies, and strategies in which hand-thrown spears were considered preferable to more complex weapons may now provide a useful avenue for understanding the context in which these weapons emerged in the first place.